Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net income	$ 161,143	$ 104,851	$ 103,700
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	75,070	71,518	68,082
Amortization of debt issue costs and accretion of discount	1,877	1,987	2,988
Operating lease amortization	5,860	5,877	6,161
Provision for doubtful accounts and sundry losses	1,859	1,726	3,939
Deferred tax benefit	(2,826)	(3,905)	(6,391)
Share-based compensation	14,799	14,253	13,570
Gain from sale of assets	(778)	0	0
Loss on disposition of property and equipment and other intangibles	1,694	807	893
Earnings of equity method investment	(1,713)	(1,136)	(936)
Dividend received from equity method investment	1,183	0	485
(Increase) decrease in assets:
Accounts receivable	(18,521)	8,397	(7,851)
Prepaid expenses and other assets	4,322	(4,158)	(8,770)
Other long-term assets	(3,519)	(611)	(1,750)
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities	(394)	(4,032)	(215)
Income tax payable	(359)	195	(596)
Unearned income	(1,738)	6,891	11,504
Operating lease liabilities	(4,869)	(5,936)	(6,055)
Other long-term liabilities	(4,670)	2,365	1,191
Total adjustments	67,277	94,238	76,249
Net cash provided by operating activities	228,420	199,089	179,949
Cash flows from investing activities
Additions to software	(41,804)	(31,558)	(36,871)
Acquisitions, net of cash acquired	(14,750)	0	(5,585)
Property and equipment acquired	(25,103)	(17,082)	(23,002)
Proceeds from sales of property and equipment	805	6	111
Acquisition of available-for-sale debt securities	(2,968)	0	0
Net cash used in investing activities	(83,820)	(48,634)	(65,347)
Cash flows from financing activities
Repayments of borrowings for purchase of equipment and software	(1,651)	(1,553)	(886)
Dividends paid	(14,409)	(14,382)	(14,420)
Withholding taxes paid on share-based compensation	(8,793)	(8,134)	(8,849)
Repurchase of common stock	(24,388)	(7,300)	(31,822)
Repayment of long-term debt	(32,044)	(31,248)	(14,250)
Net cash used in financing activities	(81,285)	(62,617)	(70,227)
Effect of foreign exchange rate on cash, cash equivalents and restricted cash	1,497	2,146	0
Net increase in cash, cash equivalents and restricted cash	64,812	89,984	44,375
Cash, cash equivalents and restricted cash at beginning of the period	221,105	131,121	86,746
Cash, cash equivalents and restricted cash at end of the period	285,917	221,105	131,121
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	266,351	202,649	111,030
Restricted cash	19,566	18,456	20,091
Cash, cash equivalents and restricted cash	285,917	221,105	131,121
Supplemental disclosure of cash flow information:
Cash paid for interest	21,695	23,787	28,233
Cash paid for income taxes	25,724	22,668	18,703
Supplemental disclosure of non-cash activities:
Payable due to vendor related to property and equipment and software acquired	$ 757	$ 1,561	$ 2,622