Schedule I Condensed Financial Information Parent - Income Statement (Details) - USD ($)	3 Months Ended								11 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Nov. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
General and administrative										$ 27,493,000	$ 41,608,000	$ 61,540,000
Total operating expenses										356,350,000	497,602,000	386,466,000
Equity in income/(loss) from subsidiaries										3,747,000	3,642,000	3,783,000
Operating income/(loss) from continuing operations										37,823,000	(31,540,000)	84,189,000
Other expense										(1,881,000)	(2,391,000)	(26,239,000)
Income/(loss) from continuing operations before interest expense, reorganization items, net and income taxes										35,942,000	(33,931,000)	57,950,000
Interest expense	$ 9,125,000	$ 9,474,000	$ 9,445,000	$ 9,357,000	$ 9,765,000	$ 10,607,000	$ 10,862,000	$ 11,917,000		37,401,000	43,151,000	70,365,000
Loss from continuing operations before reorganization items, net and income taxes										(1,459,000)	(77,082,000)	(12,415,000)
Reorganization items, net	(8,000)	(46,000)	9,000	235,000	393,000	5,732,000	860,000	(17,910,000)		190,000	(10,925,000)	8,052,000
Loss from continuing operations before income taxes										(1,649,000)	(66,157,000)	(20,467,000)
Income tax benefit	(59,679,000)	(3,110,000)	1,593,000	3,569,000	(63,653,000)	(49,755,000)	15,075,000	33,235,000		(57,627,000)	(65,098,000)	(101,032,000)
Net income/(loss) from continuing operations					64,678,000	(52,855,000)	(4,184,000)	(8,698,000)		55,978,000	(1,059,000)	80,565,000
(Loss)/income from discontinued operations					(340,153,000)	(45,884,000)	34,045,000	59,437,000		0	(292,555,000)	203,395,000
Net income/(loss)	$ 53,645,000	$ (6,307,000)	$ 3,211,000	$ 5,429,000	$ (275,475,000)	$ (98,739,000)	$ 29,861,000	$ 50,739,000		55,978,000	(293,614,000)	283,960,000
Net change in unrealized gains on cash flow hedges										907,000	10,311,000	6,927,000
Net change in unrecognized prior service cost										157,000	60,000	211,000
Net change in unrecognized actuarial losses										948,000	(3,295,000)	3,203,000
Other comprehensive income										1,698,000	6,956,000	9,919,000
Comprehensive income/(loss)										57,676,000	(286,658,000)	293,879,000
Parent Company [Member]
General and administrative										(134,000)	698,000	935,000
Total operating expenses										(134,000)	698,000	935,000
Equity in income/(loss) from subsidiaries										6,575,000	(63,698,000)	47,534,000
Operating income/(loss) from continuing operations										6,709,000	(64,396,000)	46,599,000
Other expense										(2,504,000)	(2,363,000)	(26,511,000)
Income/(loss) from continuing operations before interest expense, reorganization items, net and income taxes										4,205,000	(66,759,000)	20,088,000
Interest expense										5,664,000	10,323,000	32,669,000
Loss from continuing operations before reorganization items, net and income taxes										(1,459,000)	(77,082,000)	(12,581,000)
Reorganization items, net										190,000	(10,925,000)	7,888,000
Loss from continuing operations before income taxes										(1,649,000)	(66,157,000)	(20,469,000)
Income tax benefit										(57,627,000)	(65,098,000)	(101,034,000)
Net income/(loss) from continuing operations										55,978,000	(1,059,000)	80,565,000
(Loss)/income from discontinued operations									$ (292,555,000)	0	(292,555,000)	203,395,000
Net income/(loss)										55,978,000	(293,614,000)	283,960,000
Net change in unrealized gains on cash flow hedges										907,000	10,311,000	6,927,000
Net change in unrecognized prior service cost										157,000	60,000	211,000
Net change in unrecognized actuarial losses										948,000	(3,295,000)	3,203,000
Other comprehensive income										1,698,000	6,956,000	9,919,000
Comprehensive income/(loss)										$ 57,676,000	$ (286,658,000)	$ 293,879,000