CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 58,711	$ 82,770	$ 66,130
Adjustments to reconcile net income to net cash provided by operating activities-
Depreciation	22,926	21,422	18,304
Amortization	43,947	45,700	44,328
Amortization of original issue discount	2,983	2,819	2,664
Asset impairment	11,030	438	1,851
Gain on short-term investments and other	(123)	(364)	(101)
Loss on extinguishment of debt			810
Deferred income taxes	(1,033)	(77)	4,913
Stock-based compensation	25,237	19,919	19,358
Changes in operating assets and liabilities, net of acquired amounts:
Trade accounts receivable, net	14,659	(4,015)	(138)
Other current and non-current assets and liabilities	(10,688)	(17,727)	(23,179)
Income taxes payable/receivable	5,405	4,771	5,055
Trade accounts payable and accrued liabilities	(5,752)	(10,317)	(7,146)
Deferred revenue	5,718	5,737	10,492
Net cash provided by operating activities	173,020	151,076	143,341
Cash flows from investing activities:
Purchases of software, property and equipment	(29,397)	(37,319)	(57,104)
Purchases of short-term investments	(81,824)	(54,258)	(75,022)
Proceeds from sale/maturity of short-term investments	56,454	52,135	190,778
Acquisition of and investments in business, net of cash acquired	(11,491)	(17,194)	(144,791)
Net cash used in investing activities	(66,258)	(56,636)	(86,139)
Cash flows from financing activities:
Proceeds from issuance of common stock	2,523	2,227	2,311
Payment of cash dividends	(31,056)	(29,126)	(27,979)
Repurchase of common stock	(38,123)	(30,918)	(34,726)
Exercise of common stock warrants		(12,911)
Proceeds from long-term debt			150,000
Payments on long-term debt	(10,313)	(7,500)	(125,625)
Payments of deferred financing costs			(1,490)
Net cash used in financing activities	(76,969)	(78,228)	(37,509)
Effect of exchange rate fluctuations on cash	2,358	1,059	(2,659)
Net increase in cash and cash equivalents	32,151	17,271	17,034
Cash and cash equivalents, beginning of period	156,548	139,277	122,243
Cash and cash equivalents, end of period	188,699	156,548	139,277
Cash paid during the period for-
Interest	13,681	16,064	15,857
Income taxes	$ 22,431	$ 18,358	$ 10,426