CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows from Operating Activities:
Net income	$ 97,201	$ 97,650	$ 77,184
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	(25,703)	0
Depreciation and amortization	62,249	51,569	38,296
Provision for Doubtful Accounts	10,788	10,486	7,047
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes	12,834	11,549	15,948
Allocated Share-based Compensation Expense	27,024	22,018	16,199
Write off of Deferred Debt Issuance Cost	0	3,751	0
Gross excess tax benefits from stock-based compensation	(3,081)	(6,551)	(4,943)
Workers’ compensation and medical malpractice provision	2,693	2,117	3,321
Other Noncash Income (Expense)	(5,642)	(7,136)	(1,408)
Changes in operating assets and liabilities:
Accounts receivable	(43,289)	(53,775)	(45,361)
Prepaid expenses and income taxes	6,433	100	(8,304)
Increase (Decrease) in Income Taxes Payable	3,346	(7,679)	(8,023)
Accounts payable	(2,236)	1,684	(1,693)
Accrued payroll and contract professional pay	23,556	242	11,275
Increase (Decrease) in Workers' Compensation Liabilities	(2,691)	(901)	(2,192)
Other	561	3,800	(4,140)
Net cash provided by operating activities	196,250	117,493	96,022
Cash Flows from Investing Activities:
Cash paid for property and equipment	(27,138)	(24,689)	(19,729)
Cash paid for acquisitions, net of cash acquired	0	(552,777)	0
Proceeds from Divestiture of Businesses, Net of Cash Divested	6,000	115,440	0
Other	(846)	496	169
Net cash used in investing activities	(21,984)	(461,530)	(19,560)
Cash Flows from Financing Activities:
Principal payments of long-term debt	(129,000)	(516,125)	(148,688)
Proceeds from long-term debt	11,000	875,000	164,000
Proceeds from option exercises and employee stock purchase plan	9,758	6,591	6,358
Payment of employment taxes related to release of restricted stock awards	(7,024)	(8,823)	(6,498)
Gross excess tax benefits from stock-based compensation	3,081	6,551	4,943
Repurchase of common stock	(41,096)	(1,645)	(100,049)
Debt issuance or amendment costs	(889)	(23,890)	(467)
Payments of Merger Related Costs, Financing Activities	16,814	0	691
Payments of accrued earn-outs	(4,780)	0	0
Net cash provided by (used in) financing activities	(170,984)	337,659	(81,092)
Effect of exchange rate changes on cash and cash equivalents	(107)	(1,467)	(1,006)
Net Increase (Decrease) in Cash and Cash Equivalents	3,175	(7,845)	(5,636)
Cash and Cash Equivalents at Beginning of Year	23,869	31,714	37,350
Cash and Cash Equivalents at End of Year	27,044	23,869	31,714
Supplemental Disclosure of Cash Flow Information
Income taxes	38,190	45,478	56,320
Interest	26,829	22,282	11,559
Non-Cash Investing and Financing Activities:
Equity consideration for acquisition	0	30,183	0
Proceeds from Stock Options Exercised	0	2,174	0
Acquisition of property and equipment through accounts payable	438	989	2,932
Unsettled repurchases of common stock	$ 1,995	$ 0	$ 0