SEGMENT AND RELATED INFORMATION - SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) area	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment area	Jun. 30, 2017 USD ($)
SEGMENT AND RELATED INFORMATION
Number of operating segments | segment			2
Net revenues	$ 266,966	$ 263,386	$ 500,961	$ 497,067
Material costs	86,516	83,657	162,872	158,062
Personnel expenses	89,554	87,831	175,662	175,786
Other expenses	61,295	65,609	122,873	136,334
Depreciation & amortization	9,272	9,825	18,602	19,962
Income (loss) from operations	20,329	16,464	20,952	6,923
Interest expense, net	7,317	14,091	19,580	28,100
Loss on extinguishment of debt			16,998
Non-service defined benefit plan expense	176	184	352	368
Income (loss) before income taxes	12,836	2,189	(15,978)	(21,545)
(Benefit) provision for income taxes	(92)	552	(6,288)	(5,448)
Net income (loss)	12,928	1,637	(9,690)	(16,097)
Corporate & Other
SEGMENT AND RELATED INFORMATION
Other expenses	20,373	24,002	40,792	52,117
Depreciation & amortization	1,771	1,863	3,701	3,901
Income (loss) from operations	(22,144)	(25,865)	(44,493)	(56,018)
Interest expense, net	(2,386)	2,667	(1,377)	5,181
Loss on extinguishment of debt			16,998
Non-service defined benefit plan expense	176	184	352	368
Income (loss) before income taxes	(19,934)	(28,716)	(60,466)	(61,567)
(Benefit) provision for income taxes	(92)	552	(6,288)	(5,448)
Net income (loss)	(19,842)	(29,268)	(54,178)	(56,119)
Intersegments
SEGMENT AND RELATED INFORMATION
Net revenues	(49,835)	(45,169)	(92,357)	(86,369)
Material costs	(49,835)	(45,169)	(92,357)	(86,369)
Consolidating Adjustments
SEGMENT AND RELATED INFORMATION
Net revenues	(49,835)	(45,169)	(92,357)	(86,369)
Material costs	$ (49,835)	(45,169)	$ (92,357)	(86,369)
Patient Care
SEGMENT AND RELATED INFORMATION
Medicare reimbursement for O&P products and services based on prices set forth in fee schedules, number of regional pricing areas | area	10		10
Net revenues	$ 218,158	216,221	$ 406,665	403,858
Material costs	65,909	64,245	123,808	120,678
Personnel expenses	76,792	75,906	150,405	151,421
Other expenses	35,439	35,546	70,443	71,262
Depreciation & amortization	4,998	5,370	9,896	10,799
Income (loss) from operations	35,020	35,154	52,113	49,698
Interest expense, net	6,456	8,124	14,445	16,286
Income (loss) before income taxes	28,564	27,030	37,668	33,412
Net income (loss)	28,564	27,030	37,668	33,412
Patient Care | Operating segments
SEGMENT AND RELATED INFORMATION
Net revenues	218,158	216,221	406,665	403,858
Material costs	59,989	58,322	112,164	108,933
Patient Care | Intersegments
SEGMENT AND RELATED INFORMATION
Material costs	5,920	5,923	11,644	11,745
Products & Services
SEGMENT AND RELATED INFORMATION
Net revenues	98,643	92,334	186,653	179,578
Material costs	70,442	64,581	131,421	123,753
Personnel expenses	12,762	11,925	25,257	24,365
Other expenses	5,483	6,061	11,638	12,955
Depreciation & amortization	2,503	2,592	5,005	5,262
Income (loss) from operations	7,453	7,175	13,332	13,243
Interest expense, net	3,247	3,300	6,512	6,633
Income (loss) before income taxes	4,206	3,875	6,820	6,610
Net income (loss)	4,206	3,875	6,820	6,610
Products & Services | Operating segments
SEGMENT AND RELATED INFORMATION
Net revenues	48,808	47,165	94,296	93,209
Material costs	26,527	25,335	50,708	49,129
Products & Services | Intersegments
SEGMENT AND RELATED INFORMATION
Net revenues	49,835	45,169	92,357	86,369
Material costs	$ 43,915	$ 39,246	$ 80,713	$ 74,624