CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Cash flows provided by operating activities:
Net income (loss)	$ 5,691	$ 4,369	$ 8,775	$ (5,321)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	9,373	8,950	26,906	27,552
Amortization of right-of-use assets			27,657
Provision (benefit) for doubtful accounts			284	(578)
Stock-based compensation expense			10,089	9,573
Deferred income taxes			(723)	(4,114)
Amortization of debt discounts and issuance costs			1,202	2,453
Loss on extinguishment of debt				16,998
Gain on sale and disposal of fixed assets			(1,200)	(2,537)
Changes in operating assets and liabilities (Note T)			(53,045)	(6,867)
Net cash provided by operating activities			19,945	37,159
Cash flows used in investing activities
Purchase of property, plant, and equipment			(20,262)	(16,435)
Purchase of therapeutic program equipment leased to third parties under operating leases			(5,165)	(6,390)
Acquisitions, net of cash acquired			(31,585)
Purchase of company-owned life insurance investment				(598)
Proceeds from sale of property, plant and equipment			2,181	3,583
Net cash used in investing activities			(54,831)	(19,840)
Cash flows (used in ) provided by financing activities
Borrowings under term loan, net of discount				501,467
Repayment of term loan			(3,788)	(434,400)
Borrowings under revolving credit agreement				3,000
Repayments under revolving credit agreement				(8,000)
Payment of employee taxes on stock-based compensation			(3,710)	(2,568)
Payment on seller notes			(2,688)	(2,116)
Payment of financing lease obligations			(344)	(942)
Payment of debt issuance costs				(6,757)
Payment of debt extinguishment costs				(8,436)
Proceeds from exercise of options			249
Net cash (used in) provided by financing activities			(10,281)	41,248
(Decrease) increase in cash, cash equivalents, and restricted cash			(45,167)	58,567
Cash, cash equivalents, and restricted cash, at beginning of period			95,114	4,779	$ 4,779
Cash, cash equivalents, and restricted cash, at end of period	49,947	63,346	49,947	63,346	95,114
Reconciliation of Cash, Cash Equivalents, and Restricted Cash:
Cash and cash equivalents, at beginning of period			95,114	1,508	1,508
Restricted cash, at beginning of period				3,271	3,271
Cash, cash equivalents, and restricted cash, at beginning of period			95,114	4,779	4,779
Cash and cash equivalents, at end of period	49,947	61,035	49,947	61,035	95,114
Restricted cash, at end of period		2,311		2,311
Cash, cash equivalents, and restricted cash, at end of period	$ 49,947	$ 63,346	$ 49,947	$ 63,346	$ 95,114