| 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 |
|---|
| Net income | 26 | 24 | 27 | 28 | 29 | 28 | 37 | 34 | 37 | 32 | 33 | 35 | 19 |
|---|
| Depreciation and amortization | 7 | 8 | 9 | 9 | 9 | 9 | 9 | 9 | 11 | 12 | 13 | 14 | 15,098 |
|---|
| Deferred income taxes | - | - | - | - | - | - | - | - | - | - | - | 3 | - |
|---|
| Deferred income taxes | 3 | 1 | -1 | 0 | -1 | -0 | -1 | -1 | 2 | - | - | - | -1,517 |
|---|
| Stock-based compensation | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 1,531 |
|---|
| Net change in unrealized gains and losses on investments | - | - | - | - | - | - | - | - | 0 | -1 | -1 | -0 | 900 |
|---|
| Net change in accrued interest, premiums, and discounts on investments | - | - | - | - | - | - | - | - | - | - | - | -0 | -118 |
|---|
| Other | - | - | - | - | - | - | - | - | - | 0 | 0 | - | - |
|---|
| Adjustments to reconcile net income to net cash provided by operating activities: | - | - | - | - | - | - | - | - | 51 | 47 | 44 | 48 | 35,305 |
|---|
| Accounts receivable | -0 | 2 | 1 | 3 | -0 | 1 | -0 | -0 | 2 | 2 | -5 | 3 | 922 |
|---|
| Inventories | 7 | -1 | 2 | 2 | 2 | -1 | 0 | 4 | 9 | -8 | -0 | 15 | -16,514 |
|---|
| Prepaid expenses and other current assets | 1 | 1 | -2 | 3 | -2 | 0 | 0 | 0 | 1 | - | - | 1 | 347 |
|---|
| Other non-current assets | -0 | 0 | 0 | 0 | 0 | 1 | -0 | 0 | 0 | -0 | 0 | -1 | 480 |
|---|
| Accounts payable and accrued liabilities | 2 | -2 | 2 | 1 | -0 | -0 | 0 | 1 | 1 | 2 | -1 | -1 | -326 |
|---|
| Accrued income and other taxes | 0 | -0 | 0 | -0 | -0 | 0 | 0 | -0 | -0 | -0 | -0 | -0 | 32 |
|---|
| Other non-current liabilities | 0 | -1 | 0 | -1 | 0 | 0 | 1 | 1 | 1 | - | - | 1 | -240 |
|---|
| Cash flows from operating activities | 31 | 29 | 37 | 31 | 40 | 37 | 47 | 43 | 42 | 39 | 39 | 29 | 20,006 |
|---|
| Property, plant and equipment additions | 12 | 10 | 8 | 13 | 9 | 11 | 10 | 18 | 20 | - | - | 34 | 22,319 |
|---|
| Purchase of investments | 15 | 27 | - | 33 | 0 | 31 | 69 | 28 | 84 | - | - | 36 | 5,648 |
|---|
| Proceeds from sale of investments | - | - | - | - | - | - | - | - | - | - | - | 0 | 1,683 |
|---|
| Proceeds from maturities of investments | 14 | 20 | 8 | 36 | 13 | 5 | 58 | 41 | 59 | 36 | 40 | 54 | 22,147 |
|---|
| Cash flows from investing activities | -12 | -17 | -2 | -10 | 4 | -36 | -21 | -5 | -45 | -31 | 2 | -15 | -4,137 |
|---|
| Shares tendered for employees' withholding taxes on stock-based compensation | 0 | 1 | - | 0 | 0 | 1 | 8 | 0 | 1 | - | - | 1 | 57 |
|---|
| Purchase of treasury stock | - | - | - | - | - | - | - | - | - | - | - | 26 | - |
|---|
| Purchase of treasury stock | 2 | 5 | 9 | 24 | 31 | 1 | - | - | - | - | - | - | 1,667 |
|---|
| Dividends paid | - | - | - | - | - | - | - | - | - | - | - | -15 | - |
|---|
| Dividends paid | 4 | 24 | 5 | 5 | 6 | 7 | 8 | 9 | 11 | - | - | - | 15,311 |
|---|
| Proceeds from draw on line of credit | - | - | - | - | - | - | - | - | - | - | - | 1 | 25,607 |
|---|
| Repayment of draw on line of credit | - | - | - | - | - | - | - | - | - | - | - | 1 | 25,607 |
|---|
| Cash flows from financing activities | -5 | -29 | -14 | -29 | -37 | -9 | -16 | -10 | -11 | -31 | -31 | -41 | -17,035 |
|---|
| Net change in cash and cash equivalents | - | - | - | - | - | - | - | - | - | - | - | -28 | -1,166 |
|---|
| Income taxes, net of refunds | - | - | - | - | - | - | - | - | - | - | - | 10 | 3,536 |
|---|
| Non-cash effect of stock option exercises | - | - | - | - | - | - | - | - | - | - | 6 | 4 | - |
|---|