CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES
Net income/(loss)	$ 29,844	$ 41,874	$ (17,143)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Bad debt expense	21,768	22,222	13,291
Depreciation and amortization	42,976	40,168	28,561
Impairment charge	0	0	12,045
Stock-based compensation	13,376	9,261	7,680
Write off of derivative premium	0	0	1,322
Accretion of debt discount	1,243	1,243	678
Loss on extinguishment of debt	0	0	543
Gain on legal settlement	0	0	(1,333)
Deferred income taxes	7,385	(2,294)	6,050
Change in fair value of acquisition-related contingent consideration	(230)	(700)	(2,605)
Other non-cash items	1,018	254	(39)
Changes in operating assets and liabilities:
Healthcare and other accounts receivable	(55,027)	(35,742)	(15,455)
Inventory	1,585	(1,991)	665
Prepaid expenses and other assets	1,742	3,517	(694)
Accounts payable	5,551	3,760	(8,320)
Accrued and other liabilities	(3,681)	(8,826)	(1,464)
Net cash provided by operating activities	67,550	72,746	23,782
INVESTING ACTIVITIES
Acquisition of businesses, net of cash acquired	(44,766)	(3,750)	(161,479)
Purchases of property and equipment and investment in internally developed software	(30,707)	(24,637)	(13,697)
Purchase of derivative instrument	0	0	(1,322)
Investment in equity method investee	0	(464)	(690)
Net cash used in investing activities	(75,473)	(28,851)	(177,188)
FINANCING ACTIVITIES
Proceeds related to the exercising of stock options and employee stock purchase plan	7,610	12,186	6,071
Payments of tax withholdings related to vesting of share-based awards	(4,955)	(2,910)	(1,933)
Issuance of long-term debt	0	0	205,000
Repayments on revolving loans	0	0	(3,000)
Payment of debt issuance costs	0	0	(6,213)
Principal payments on long-term debt	(5,125)	(2,050)	(25,840)
Principal payments on finance lease obligations	(1,909)	(3,740)	(2,863)
Acquisition of noncontrolling interests	0	(2,885)	(4,765)
Net cash (used in)/provided by financing activities	(4,379)	601	166,457
Effect of exchange rate changes on cash	27	371	(81)
Net (decrease)/increase in cash and cash equivalents	(12,275)	44,867	12,970
Cash and cash equivalents—beginning of period	80,889	36,022	23,052
Cash and cash equivalents—end of period	68,614	80,889	36,022
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Non-cash purchases of property and equipment	3,302	505	498
Non-cash fair value of common stock returned in legal settlement	0	0	2,753
Non-cash fair value of equity issued for acquisition of business	2,142	0	117,440
Non-cash fair value of non-trade receivables exchanged for investment in equity method investee	0	395	0
Cash paid for interest	8,029	7,836	3,888
Cash paid for taxes, net of refunds	$ (89)	$ 763	$ 1,648