| Dec 31, 2011 | Dec 31, 2012 | Dec 31, 2013 | Dec 31, 2014 | Dec 31, 2015 | Dec 31, 2016 | Dec 31, 2017 | Dec 31, 2018 | Dec 31, 2019 | Dec 31, 2020 | Dec 31, 2021 | Dec 31, 2022 | Dec 31, 2023 | Dec 31, 2024 |
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| Cash and cash equivalents | 34 | 20 | 76 | 78 | 40 | 24 | 5 | 8 | 12 | 23 | 82 | 51 | 25 | 3 |
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| Accounts Receivable, after Allowance for Credit Loss, Current | 127 | 167 | 173 | 158 | 187 | 235 | 283 | 288 | 388 | 386 | 375 | 473 | 522 | 653 |
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| Contract assets, net of allowances of $422 and $610, respectively | - | - | - | - | - | - | - | 160 | 217 | 186 | 225 | 301 | 421 | 302 |
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| Insurance Settlements Receivable, Current | - | - | - | - | - | - | 4 | 11 | 6 | 12 | 11 | 9 | 8 | 9 |
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| Refundable income taxes | 1 | 1 | 1 | 2 | 6 | 2 | 0 | - | 2 | 2 | 9 | 9 | 4 | 5 |
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| Prepaid expenses and other current assets | - | - | - | - | - | - | - | - | - | - | 46 | 48 | 47 | 42 |
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| Total current assets | 236 | 278 | 324 | 314 | 303 | 358 | 380 | 476 | 639 | 637 | 748 | 890 | 1,026 | 1,015 |
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| Property and equipment, net of accumulated depreciation of $387,223 and $380,465, respectively | - | - | - | - | - | - | - | - | - | 185 | 196 | 233 | 269 | 278 |
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| Operating lease right-of-use assets | - | - | - | - | - | - | - | - | 23 | 22 | 21 | 31 | 35 | 43 |
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| Goodwill | 47 | 47 | 47 | 47 | 47 | 47 | 47 | 57 | 66 | 66 | 66 | 116 | 117 | 113 |
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| Intangible assets, net of accumulated amortization of $34,573 and $30,534, respectively | 11 | 11 | 10 | 10 | 11 | 12 | 11 | 33 | 55 | 51 | 49 | 88 | 84 | 76 |
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| Insurance Settlements Receivable, Noncurrent | - | - | - | - | - | - | 14 | 17 | 31 | 27 | 32 | 34 | 34 | 35 |
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| Deferred income taxes | - | - | - | - | - | - | - | - | - | - | - | - | - | 6 |
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| Investment in joint venture | - | - | - | - | - | - | 0 | 1 | 5 | 3 | 4 | 4 | 9 | 4 |
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| Other assets | 2 | 2 | 2 | 1 | 2 | 3 | 4 | 3 | 4 | 4 | 4 | 4 | 6 | 6 |
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| Total assets | 413 | 466 | 525 | 520 | 525 | 573 | 604 | 749 | 1,008 | 996 | 1,121 | 1,399 | 1,579 | 1,574 |
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| Current portion of long-term debt | - | - | - | - | - | - | - | 4 | 9 | 4 | 1 | 5 | 7 | 4 |
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| Operating Lease, Liability, Current | - | - | - | - | - | - | - | - | 6 | 7 | 8 | 10 | 9 | 12 |
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| Finance Lease, Liability, Current | - | - | - | - | - | - | - | - | 1 | 0 | - | 1 | 2 | 1 |
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| Accounts payable | 74 | 84 | 80 | 62 | 73 | 100 | 110 | 139 | 192 | 163 | 201 | 315 | 359 | 295 |
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| Contract liabilities | - | - | - | - | - | - | - | 59 | 105 | 158 | 168 | 227 | 240 | 322 |
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| Self Insurance Reserve, Current | 39 | 40 | 39 | 39 | 37 | 43 | 13 | 20 | 19 | 24 | 24 | 29 | 28 | 26 |
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| Accrued income taxes | - | - | - | - | - | - | - | - | - | - | 2 | - | 0 | 0 |
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| Other current liabilities | 29 | 32 | 33 | 32 | 29 | 42 | 35 | 61 | 64 | 87 | 95 | 80 | 101 | 88 |
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| Total current liabilities | 177 | 189 | 204 | 172 | 180 | 228 | 189 | 284 | 397 | 443 | 499 | 667 | 747 | 749 |
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| Deferred income tax liabilities | - | - | - | - | - | - | - | 17 | 21 | 18 | 25 | 46 | 48 | 52 |
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| Long-term debt | - | - | - | - | - | 59 | 79 | 86 | 157 | 25 | 3 | 35 | 29 | 70 |
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| Accrued self-insurance | - | - | - | - | - | - | 32 | 34 | 48 | 45 | 51 | 51 | 52 | 54 |
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| Operating Lease, Liability, Noncurrent | - | - | - | - | - | - | - | - | 17 | 16 | 13 | 21 | 26 | 30 |
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| Finance Lease, Liability, Noncurrent | - | - | - | - | - | - | - | - | 0 | - | - | 2 | 0 | 2 |
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| Other liabilities | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 3 | 19 | 11 | 16 | 25 | 16 |
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| Total liabilities | 197 | 212 | 229 | 198 | 195 | 310 | 317 | 424 | 643 | 567 | 602 | 839 | 928 | 974 |
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| Preferred Stock, Value, Outstanding | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
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| Common Stock, Value, Issued | - | - | - | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
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| Additional paid-in capital | 150 | 155 | 161 | 151 | 161 | 140 | 144 | 148 | 153 | 159 | 164 | 161 | 162 | 159 |
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| Accumulated other comprehensive loss | - | - | - | - | 0 | -0 | -0 | -0 | -0 | 0 | 0 | -6 | -4 | -13 |
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| Retained earnings | 66 | 100 | 135 | 171 | 168 | 123 | 143 | 175 | 212 | 270 | 355 | 405 | 493 | 454 |
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| Total shareholders’ equity | 216 | 255 | 296 | 323 | 330 | 263 | 287 | 324 | 364 | 429 | 519 | 560 | 651 | 600 |
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| Total liabilities and shareholders’ equity | 413 | 466 | 525 | 520 | 525 | 573 | 604 | 749 | 1,008 | 996 | 1,121 | 1,399 | 1,579 | 1,574 |
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