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	$ 185,184	$ 127,907	$ 120,129
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28,802	18,428	13,261
Non-cash compensation	26,730	25,040	17,887
Non-cash 401(k) employer match	0	10,509	8,976
Amortization and impairment of operating lease right of use assets	39,140	35,905	0
(Gain) loss on disposal of property and equipment	(30)	141	714
Loss on sale of equity method investment	2,980	0	0
Write-off of other comprehensive income	(15)	0	0
Deferred income taxes	(26,560)	13,466	20,271
Equity in earnings from equity method investments	(3,966)	(5,338)	(7,692)
Amortization of deferred debt issuance costs/debt discount	869	873	797
Return on equity investment	5,444	4,955	6,158
Asset impairment charge	4,152	1,470	0
Changes in operating assets and liabilities, net of impact of acquisitions:
Patient accounts receivable	2,114	(24,146)	12,224
Other current assets	(7,181)	(2,682)	8,679
Other assets	31	832	2,947
Accounts payable	1,941	(11,329)	3,165
Accrued expenses	39,839	42,096	13,524
Other long-term obligations	27,717	(329)	2,443
Operating lease liabilities	(34,695)	(32,295)	0
Operating lease right of use assets	(3,544)	(3,503)	0
Net cash provided by operating activities	288,952	202,000	223,483
Cash Flows from Investing Activities:
Proceeds from sale of deferred compensation plan assets	101	448	715
Proceeds from the sale of property and equipment	80	162	54
Purchases of property and equipment	(5,332)	(7,888)	(6,558)
Investments in equity method investees	(875)	(210)	(7,144)
Proceeds from sale of equity method investment	17,876	0	0
Acquisitions of businesses, net of cash acquired	(298,958)	(345,460)	(9,260)
Net cash used in investing activities	(287,108)	(352,948)	(22,193)
Cash Flows from Financing Activities:
Proceeds from issuance of stock upon exercise of stock options	6,325	3,611	5,953
Proceeds from issuance of stock to employee stock purchase plan	3,562	3,187	2,429
Shares withheld to pay taxes on non-cash compensation	(54,493)	(9,556)	(6,570)
Non-controlling interest distribution	(1,122)	(1,062)	(1,090)
Proceeds from borrowings under term loan	0	175,000	0
Proceeds from borrowings under revolving line of credit	684,200	262,500	138,000
Repayments of borrowings under revolving line of credit	(703,200)	(200,000)	(130,500)
Principal payments of long-term obligations	(10,249)	(5,624)	(91,450)
Debt issuance costs	0	(847)	(2,433)
Provider relief fund advance	60,000	0	0
Purchase of company stock	0	0	(181,402)
Repurchase of noncontrolling interest	0	0	(361)
Net cash (used in) provided by financing activities	(14,977)	227,209	(267,424)
Net (decrease) increase in cash, cash equivalents and restricted cash	(13,133)	76,261	(66,134)
Cash, cash equivalents and restricted cash at beginning of period	96,490	20,229	86,363
Cash, cash equivalents and restricted cash at end of period	83,357	96,490	20,229
Supplemental Disclosures of Cash Flow Information:
Cash paid for interest	6,207	9,628	3,522
Cash paid for income taxes, net of refunds received	50,721	29,522	14,278
Supplemental Disclosures of Non-Cash Financing Activity:
Note payable issued for software licenses	$ 0	$ 0	$ 418