UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 69,391	$ 35,909
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs	167	167
Amortization of investment discount/premium	68	220
Depreciation and amortization	51,981	52,497
Deferred income taxes	(6,736)	9,909
Stock-based compensation	6,884	6,576
Impairment of right-of-use lease assets	453	0
Changes in assets and liabilities:
Tuition receivable, net	3,820	5,777
Other assets	(6,338)	(1,240)
Accounts payable and accrued expenses	(22,180)	229
Income taxes payable and income taxes receivable	15,303	(10,673)
Contract liabilities	2,053	4,778
Other long-term liabilities	(2,925)	(1,086)
Net cash provided by operating activities	111,941	103,063
Cash flows from investing activities:
Purchases of property and equipment	(25,465)	(18,859)
Purchases of marketable securities	(1,863)	(12,443)
Proceeds from marketable securities	18,869	22,560
Other investments	(693)	(740)
Net cash used in investing activities	(9,152)	(9,482)
Cash flows from financing activities:
Common dividends paid	(26,662)	(22,194)
Net payments for stock awards	(24,758)	(7,607)
Repurchase of common stock	(247)	0
Net cash used in financing activities	(51,667)	(29,801)
Net increase in cash, cash equivalents, and restricted cash	51,122	63,780
Cash, cash equivalents, and restricted cash — beginning of period	420,497	312,237
Cash, cash equivalents, and restricted cash — end of period	471,619	376,017
Noncash transactions:
Non-cash additions to property and equipment	2,229	2,578
Right-of-use lease assets obtained in exchange for operating lease liabilities	$ 7,870	$ 2,298