CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income	$ 120,129	$ 30,683	$ 37,631
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,261	17,123	19,678
Non-cash compensation	17,887	16,295	16,401
401(k) employer match	8,976	8,754	6,875
Write-off of investment	0	0	196
Loss on disposal of property and equipment	714	0	582
Deferred income taxes	20,271	52,178	24,547
Equity in earnings from equity method investments	(7,692)	(3,381)	(5,588)
Amortization of deferred debt issuance costs/debt discount	797	735	740
Return on equity investment	6,158	5,321	4,323
Asset impairment charge	0	1,323	4,432
Changes in operating assets and liabilities, net of impact of acquisitions:
Patient accounts receivable	12,224	(34,672)	(36,000)
Other current assets	8,679	(4,940)	4,231
Other assets	2,947	(12,749)	(11,415)
Accounts payable	3,165	(2,843)	3,970
Accrued expenses	13,524	31,843	(7,618)
Other long-term obligations	2,443	61	(726)
Net cash provided by operating activities	223,483	105,731	62,259
Cash Flows from Investing Activities:
Proceeds from sale of deferred compensation plan assets	715	622	230
Proceeds from the sale of property and equipment	54	249	0
Purchases of property and equipment	(6,558)	(10,707)	(15,717)
Investments in equity method investees	(7,144)	(476)	(1,040)
Acquisitions of businesses, net of cash acquired	(9,260)	(33,715)	(35,522)
Net cash used in investing activities	(22,193)	(44,027)	(52,049)
Cash Flows from Financing Activities:
Proceeds from issuance of stock upon exercise of stock options	5,953	4,554	0
Proceeds from issuance of stock to employee stock purchase plan	2,429	2,382	2,483
Shares withheld upon stock vesting	(6,570)	(6,939)	0
Tax benefit from stock options exercised and restricted stock vesting	0	0	7,241
Non-controlling interest distribution	(1,090)	(216)	(329)
Proceeds from borrowings under revolving line of credit	138,000	0	134,500
Repayments of borrowings under revolving line of credit	(130,500)	0	(134,500)
Principal payments of long-term obligations	(91,450)	(5,319)	(5,000)
Debt issuance costs	(2,433)	0	0
Purchase of company stock	(181,402)	0	(12,315)
Assets contributed to equity investment	0	0	405
Repurchase of noncontrolling interest	(361)	0	0
Net cash used in financing activities	(267,424)	(5,538)	(7,515)
Net (decrease) increase in cash and cash equivalents	(66,134)	56,166	2,695
Cash and cash equivalents at beginning of period	86,363	30,197	27,502
Cash and cash equivalents at end of period	20,229	86,363	30,197
Supplemental Disclosures of Cash Flow Information:
Cash paid for interest	3,522	2,697	2,897
Cash paid for income taxes, net of refunds received	14,278	315	755
Supplemental Disclosures of Non-Cash Financing Activities:
Note payable issued for software licenses	418	0	0
Capital leases	$ 2,936	$ 0	$ 0