Summarized Quarterly Financial Information (Unaudited) - Schedule (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Operating revenues	$ 272,692	$ 233,040	$ 227,817	$ 209,498	$ 204,808	$ 189,691	$ 198,134	$ 123,023	$ 943,047	$ 715,656	$ 498,752
Costs and expenses	(190,549)	(190,797)	(189,699)	(186,228)	(223,095)	(173,962)	(200,209)	(124,214)	(757,273)	(721,480)	(443,911)
Depreciation and amortization of intangibles	(14,492)	(14,892)	(14,786)	(14,411)	(14,018)	(16,273)	(13,366)	(8,295)	(58,581)	(51,952)	(32,180)
Impairment of goodwill and intangibles	0	0				(24,613)			0	(24,613)	0
Gains (losses), net on disposal of property and equipment	(499)	(26)	(22)	4	96	(200)	(215)	(164)	(543)	(483)	2,872
Interest expense	(4,436)	(4,592)	(4,432)	(4,579)	(4,576)	(4,246)	(4,225)	(2,052)	(18,039)	(15,099)	(8,494)
Miscellaneous, net	(1,401)	(596)	(458)	(191)	(1,433)	1,061	387	(1,436)	(2,646)	(1,421)	(7,693)
Income (loss) from continuing operations before income taxes	61,315	22,137	18,420	4,093	(38,218)	(28,542)	(19,494)	(13,138)	105,965	(99,392)	9,346
Provision (benefit) for income taxes	22,978	9,615	6,932	(795)	(17,094)	(4,099)	(6,539)	(5,023)	38,730	(32,755)	(111)
Net (loss) income from continuing operations	38,337	12,522	11,488	4,888	(21,124)	(24,443)	(12,955)	(8,115)	67,235	(66,637)
Net (loss) income from discontinued operations, net of tax	0	0	0	0	(407)	0	(18,448)	3,015	0	(15,840)	1,072
Net income (loss)	$ 38,337	$ 12,522	$ 11,488	$ 4,888	$ (21,531)	$ (24,443)	$ (31,403)	$ (5,100)	$ 67,235	$ (82,477)	$ 10,529
Income (loss) from continuing operations, per basic share	$ 0.46	$ 0.15	$ 0.14	$ 0.06	$ (0.25)	$ (0.29)	$ (0.15)	$ (0.14)	$ 0.80	$ (0.86)	$ 0.16
(Loss) income from discontinued operations, per basic share	0.00	0.00	0.00	0.00	0.00	0.00	(0.22)	0.05	0.00	(0.20)	0.02
Income (loss) from continuing operations, per diluted share	0.46	0.15	0.13	0.06	(0.25)	(0.29)	(0.15)	(0.14)	0.79	(0.86)	0.16
(Loss) income from discontinued operations, per diluted share	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.22)	$ 0.05	$ 0.00	$ (0.20)	$ 0.02
Basic weighted-average shares outstanding	82,401	83,230	83,773	83,965	83,775	84,107	83,903	57,335	83,339	77,373	56,342
Diluted weighted-average shares outstanding	82,684	83,518	84,051	84,225	83,775	84,107	83,903	57,335	83,639	77,373	57,239
Cash dividends per share of common stock (USD per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0	$ 0	$ 1.03	$ 0	$ 0	$ 1.03	$ 0