CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	8 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Apr. 30, 2014
Income Statement [Abstract]
Revenues	$ 368,374	$ 565,030	$ 546,500	$ 497,633
Operating expenses:
Cost of operations	258,650	381,973	382,615	354,592
General and administration	45,732	75,356	72,892	61,865
Depreciation and amortization	41,485	61,856	62,704	60,339
Environmental remediation charge	950	900	0	400
Contract settlement charge	0	0	1,940	0
Divestiture transactions	(553)	0	(5,517)	7,455
Development project charge	0	0	0	1,394
Severance and reorganization costs	0	0	0	586
Expense from divestiture, acquisition and financing costs	0	0	0	144
Gain on settlement of acquisition related contingent consideration	0	0	0	(1,058)
Total operating expenses	346,264	520,085	514,634	485,717
Operating income	22,110	44,945	31,866	11,916
Other expense (income):
Interest income	(247)	(290)	(330)	(312)
Interest expense	25,639	38,942	40,420	38,175
Loss on debt extinguishment	0	13,747	999	0
Loss on derivative instruments	225	0	227	280
Impairment of investments	2,320	0	2,099	0
Loss from equity method investments	0	0	0	936
Gain on sale of equity method investment	0	0	0	(593)
Other income	(720)	(1,090)	(1,119)	(1,059)
Other expense, net	27,217	51,309	42,296	37,427
Loss from continuing operations before income taxes and discontinued operations	(5,107)	(6,364)	(10,430)	(25,511)
Provision for income taxes	703	494	1,351	1,799
Loss from continuing operations before discontinued operations	(5,810)	(6,858)	(11,781)	(27,310)
Discontinued operations:
Income from discontinued operations, net of income tax provision of $0, $0, $0 and $0	0	0	0	284
Loss on disposal of discontinued operations, net of income tax provision of $0, $0, $0 and $0	0	0	0	(378)
Net loss	(5,810)	(6,858)	(11,781)	(27,404)
Less: Net (loss) income attributable to noncontrolling interests	208	(9)	1,188	(4,309)
Net loss attributable to common stockholders	(6,018)	(6,849)	(12,969)	(23,095)
Net loss attributable to common stockholders:
Continuing operations, net of tax	(6,018)	(6,849)	(12,969)	(23,001)
Discontinued operations, net of tax	0	0	0	(94)
Net loss attributable to common stockholders	$ (6,018)	$ (6,849)	$ (12,969)	$ (23,095)
Weighted average common shares outstanding:
Weighted average common shares outstanding, basic and diluted (in shares)	40,262	41,233	40,642	39,820
Basic and diluted earnings per share:
Basic and diluted earnings per share, Continuing operations, net of tax (in USD per share)	$ (0.15)	$ (0.17)	$ (0.32)	$ (0.58)
Basic and diluted earnings per share, Discontinued operations, net of tax (in USD per share)	0.00	0.00	0.00	0.00
Net loss per common share (in USD per share)	$ (0.15)	$ (0.17)	$ (0.32)	$ (0.58)