Industry Segments - Corporate Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
General and administrative expense	$ 34,446	$ 29,685	$ 98,866	$ 85,896
Depreciation, amortization, and accretion	29,460	25,942	84,880	78,250
Other (income) expense, net	619	(425)	7,203	811
Warrants fair value adjustment			22	(11,568)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	12,852	857	46,041	13,068
Interest expense, net	18,894	14,654	52,246	42,749
Corporate Overhead [Member]
Segment Reporting Information [Line Items]
General and administrative expense	13,037	12,277	37,506	33,883
Depreciation, amortization, and accretion	172	129	487	338
Other (income) expense, net	1,333	293	1,703	1,026
Warrants fair value adjustment	(179)	(47)	22	(11,568)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	19,631	16,551	53,870	35,592
Interest expense, net	$ 5,268	$ 3,899	$ 14,152	$ 11,913