Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 85,171	$ 97,213
Adjustments to reconcile net income to net cash provided by operating activities:
Asset impairment		612
Depreciation and amortization expense	11,802	10,785
Bad debt expense	36,360	36,706
Compensation expense related to share-based awards	11,287	9,735
Deferred income taxes	9,938	11,339
Changes in operating assets and liabilities	(10,352)	(28,637)
Net cash provided by operating activities	144,206	137,753
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of available-for-sale investments	(269,739)	(333,767)
Sales of available-for-sale investments	357,280	213,576
Purchases of property and equipment	(6,276)	(7,479)
Business acquisitions, net of cash acquired	(56,947)	(39,819)
Net cash provided by (used in) investing activities	24,318	(167,489)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock	793	1,925
Purchase of treasury stock	(5,372)	(17,862)
Payments of employee tax associated with stock compensation	(2,034)	(894)
Net cash used in financing activities	(6,613)	(16,831)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	161,911	(46,567)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, beginning of the period	109,684	108,687
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of the period	271,595	62,120
Supplemental non-cash disclosure:
Amounts placed in escrow during the period to secure indemnification obligations from business acquisitions	$ 1,210	$ 4,000