Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 57,402	$ 57,273
Adjustments to reconcile net income to net cash provided by operating activities:
Asset impairment		612
Depreciation and amortization expense	7,915	6,790
Bad debt expense	26,168	25,187
Compensation expense related to share-based awards	7,430	6,503
Deferred income taxes	8,569	19,262
Changes in operating assets and liabilities	(24,739)	(10,263)
Net cash provided by operating activities	82,745	105,364
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of available-for-sale investments	(218,437)	(209,846)
Sales of available-for-sale investments	127,193	145,819
Purchases of property and equipment	(3,059)	(3,439)
Business acquisition		(34,065)
Net cash used in investing activities	(94,303)	(101,531)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock	623	1,014
Purchase of treasury stock	(5,372)	(17,309)
Payments of employee tax associated with stock compensation	(2,034)	(689)
Net cash used in financing activities	(6,783)	(16,984)
NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(18,341)	(13,151)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, beginning of the period	109,684	108,687
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of the period	$ 91,343	95,536
Supplemental non-cash disclosure:
Amounts placed in escrow during the period to secure indemnification obligations from business acquisition		$ 4,000