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	$ 55,087	$ 86,268	$ 81,138
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on sale of marketable securities	781	0	0
Gain on sale of property and equipment	(2,656)	0	0
Amortization of deferred financing costs	552	466	333
Amortization of investment discount/premium	70	146	296
Depreciation and amortization	103,416	109,154	104,861
Deferred income taxes	(7,710)	(13,431)	(8,037)
Stock-based compensation	18,149	14,610	12,160
Impairment of right-of-use lease assets	18,876	848	6,046
Changes in assets and liabilities:
Tuition receivable, net	(196)	19,659	1,770
Other assets	(6,964)	(32,326)	(2,129)
Accounts payable and accrued expenses	(6,700)	(22,685)	245
Income taxes payable and income taxes receivable	1,196	(4,020)	1,198
Contract liabilities	13,995	(10,095)	7,716
Other liabilities	(7,369)	(5,689)	(3,451)
Net cash provided by operating activities	180,527	142,905	202,146
Cash flows from investing activities:
Cash paid for acquisition, net of cash acquired	0	(628,759)	0
Purchases of property and equipment	(49,433)	(46,812)	(38,689)
Purchases of marketable securities	0	(1,863)	(40,481)
Proceeds from marketable securities	9,300	36,192	43,762
Proceeds from sale of property and equipment	8,331	0	0
Other investments	(1,292)	(950)	(2,658)
Net cash used in investing activities	(33,094)	(642,192)	(38,066)
Cash flows from financing activities:
Net proceeds from issuance of common stock	0	220,248	0
Proceeds from long-term debt	0	145,630	0
Common dividends paid	(59,045)	(55,956)	(46,625)
Net payments for stock awards	(2,938)	(24,741)	(9,195)
Payments on long-term debt	0	(3,807)	0
Payment of deferred financing costs	0	(1,940)	0
Repurchase of common stock	(5,905)	(247)	0
Net cash provided by (used in) financing activities	(67,888)	279,187	(55,820)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(2,353)	1,623	0
Net increase (decrease) in cash, cash equivalents, and restricted cash	77,192	(218,477)	108,260
Cash, cash equivalents, and restricted cash - beginning of period	202,020	420,497	312,237
Cash, cash equivalents, and restricted cash - end of period	279,212	202,020	420,497
Noncash transactions:
Non-cash additions to property and equipment	$ 9,308	$ 4,079	$ 5,562