Condended Financial Information of Registrant Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating expenses
Depreciation and amortization									$ 52,642	$ 45,989	$ 31,617
General and administrative expense (excluding depreciation)									47,426	46,078	42,073
Acquisition and integration costs									10,319	395	5,294
Total operating expenses									3,328,787	2,349,105	1,884,694
Operating income (loss)	$ 20,408	$ 4,894	$ 28,983	$ 27,656	$ 21,605	$ 26,716	$ 16,451	$ 29,189	81,941	93,961	(19,649)
Other income (expense)
Interest expense and financing costs, net									(39,768)	(31,632)	(28,506)
Other income (expense), net									1,046	911	(10)
Change in value of common stock warrants									1,801	(1,674)	2,962
Equity earnings (losses) of subsidiaries									9,464	18,369	(22,381)
Total other expense, net									(42,181)	(22,659)	(34,098)
Income (loss) before income taxes									39,760	71,302	(53,747)
Income tax benefit (expense)									(333)	1,319	7,912
Net income (loss)	$ 13,886	$ (5,822)	$ 16,178	$ 15,185	$ 19,005	$ 18,824	$ 7,006	$ 27,786	39,427	72,621	(45,835)
Parent Company
Operating expenses
Depreciation and amortization									4,092	2,871	2,205
General and administrative expense (excluding depreciation)									20,721	18,922	15,618
Acquisition and integration costs									10,118	192	4,781
Total operating expenses									34,931	21,985	22,604
Operating income (loss)									(34,931)	(21,985)	(22,604)
Other income (expense)
Interest expense and financing costs, net									(10,867)	(13,709)	(18,246)
Debt extinguishment and commitment costs									0	(1,804)	0
Interest income from subsidiaries									0	0	583
Other income (expense), net									1,155	631	67
Change in value of common stock warrants									1,801	(1,674)	2,962
Equity earnings (losses) of subsidiaries									81,942	111,162	(17,170)
Total other expense, net									74,031	94,606	(31,804)
Income (loss) before income taxes									39,100	72,621	(54,408)
Income tax benefit (expense)									327	0	8,573
Net income (loss)									$ 39,427	$ 72,621	$ (45,835)