Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	Mar. 17, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue from services		$ 219,674	$ 228,488	$ 209,313	$ 207,573	$ 222,523	$ 214,988	$ 199,443	$ 196,583	$ 865,048	$ 833,537	$ 767,421
Gross profit (a)		58,303	60,480	56,528	53,275	57,633	58,210	54,846	51,046
Consolidated net (loss) income		28,256	7,044	5,220	(1,718)	(7,649)	14,289	(17,095)	19,186	38,802	8,731	4,954
Net (loss) income attributable to common shareholders		$ 27,950	$ 6,723	$ 4,850	$ (2,010)	$ (7,884)	$ 14,066	$ (17,237)	$ 19,022	$ 37,513	$ 7,967	$ 4,418
Net income (loss) per share attributable to common shareholders - Basic (usd per share)		$ 0.78	$ 0.19	$ 0.14	$ (0.06)	$ (0.24)	$ 0.44	$ (0.54)	$ 0.60	$ 1.07	$ 0.25	$ 0.14
Net income (loss) per share attributable to common shareholders - Diluted (usd per share)		$ 0.77	$ 0.19	$ 0.13	$ (0.08)	$ (0.24)	$ 0.22	$ (0.54)	$ 0.09	$ 1.01	$ 0.15	$ 0.14
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Gain) loss on derivative liability					$ (1,600)	$ 14,200	$ (7,100)	$ 3,600	$ (16,400)	$ (1,581)	$ (5,805)	$ 9,901
Impairment charges		$ 14,400						24,300		14,356	24,311	2,100
Loss on extinguishment of debt										4,969	1,568	0
Acquisition-related contingent consideration expense (benefit)										44	814	0
Restructuring costs										1,026	$ 753	$ 1,274
Reduction in valuation allowance										45,400
Income tax expense related to deferred tax asset		8,000								$ 200
Convertible Notes
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on extinguishment of debt	$ 5,000				5,000
Second Lien Term Loan, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on extinguishment of debt								1,600
Second Lien Term Loan, net | Subordinated Debt
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on extinguishment of debt								1,600
Mediscan and USR
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Acquisition-related contingent consideration expense (benefit)		100	$ (600)	$ 300	$ 300	100	200	$ 200	$ 300
Centralization of Corporate Functions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring costs		300	$ 700			$ 200	$ 600
Remeasurement of deferred tax assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reduction in valuation allowance		$ 43,300