CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net income	$ 143,616	$ 137,933	$ 113,852
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	20,917	21,249	18,254
Amortization and impairment of operating lease right of use asset	37,506	34,546	33,368
Stock-based compensation expense	15,868	14,347	9,646
Deferred income taxes	22,789	(13,261)	18,400
(Gain) loss on disposal of assets	(1,134)	412	802
Impairment of intangibles and other	937	1,849	7,734
Changes in operating assets and liabilities, net of acquisitions:
Receivables	(35,361)	(16,561)	(38,907)
Prepaid expenses	(5,902)	(754)	3,530
Other assets	(11,015)	(3,169)	(2,923)
Prepaid income taxes	(7,531)	9,652	(78)
Accounts payable and accrued expenses	12,345	(22,506)	(457)
Salaries, wages, and benefits payable and self-insurance reserves	3,004	6,482	(2,625)
Other long term liabilities	(26,758)	51,856	0
Contract liabilities - deferred revenue	(211,473)	317,962	0
Operating lease payable	(37,360)	(34,226)	(28,062)
Income tax payable	(20,347)	23,800	(431)
Net amounts due to/from governmental entities	(433)	(364)	(1,641)
Net cash (used in) provided by operating activities	(100,332)	529,247	130,462
Investing activities:
Cash paid for acquisitions, net of cash acquired	(569,583)	(24,545)	(74,293)
Minority interest investments	(10,100)	0	0
Proceeds from sale of assets	3,350	7,920	0
Proceeds from sale of an entity	1,531	0	0
Purchases of property, building and equipment	(32,976)	(65,875)	(33,609)
Net cash used in investing activities	(607,778)	(82,500)	(107,902)
Financing activities:
Proceeds from line of credit	1,025,559	296,229	267,000
Payments on line of credit	(384,362)	(529,229)	(249,000)
Government stimulus advance	(93,257)	93,257	0
Proceeds from employee stock purchase plan	2,472	2,177	2,066
Payments on debt	0	0	(7,650)
Payments on deferred financing fees	(3,556)	0	0
Payments on repurchasing common stock	(74,643)	0	0
Noncontrolling interest distributions	(28,857)	(24,837)	(24,082)
Purchase of additional controlling interest	(2,113)	(24,295)	(19,663)
Sale of noncontrolling interest	1,934	4,856	756
Withholding taxes paid on stock-based compensation	(11,827)	(10,008)	(10,687)
Exercise of options	0	0	1,009
Net cash provided by (used in) financing activities	431,350	(191,850)	(40,251)
Change in cash	(276,760)	254,897	(17,691)
Cash at beginning of period	286,569	31,672	49,363
Cash at end of period	9,809	286,569	31,672
Supplemental disclosures of cash flow information
Interest paid	4,168	5,011	11,015
Income taxes paid	43,728	16,830	10,109
Non-Cash Operating activity:
Operating right of use assets in exchange for lease obligations	41,364	43,047	129,290
Non-Cash Investing activity:
Accrued capital expenditures	417	2,922	2,729
Net working capital adjustment	890	0	0
Non-Cash Financing activity:
Contribution of noncontrolling interest	$ 0	$ 230	$ 0