Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Revenues	$ 207,141	$ 221,569	$ 620,514	$ 649,641
Operating expenses:
Cost of services and sales, excluding depreciation and amortization	95,830	100,718	294,171	333,067
Other post-employment benefit and pension expense	(67,428)	(57,568)	(174,142)	(116,926)
Selling, general and administrative expense, excluding depreciation and amortization	45,838	49,688	145,614	158,968
Depreciation and amortization	54,918	56,296	167,661	167,420
Reorganization related expense	0	6	0	33
Total operating expenses	129,158	149,140	433,304	542,562
Income from operations	77,983	72,429	187,210	107,079
Interest expense	(20,698)	(20,186)	(61,891)	(59,979)
Other, net	91	153	344	425
Total other expense	(20,607)	(20,033)	(61,547)	(59,554)
Income before income taxes	57,376	52,396	125,663	47,525
Income tax (expense)/benefit	(17,169)	658	(37,573)	581
Net income	$ 40,207	$ 53,054	$ 88,090	$ 48,106
Weighted average shares outstanding:
Basic, in shares	26,869,658	26,676,385	26,846,546	26,640,103
Diluted, in shares	27,084,175	27,003,833	27,041,021	26,952,296
Income per share, basic (in dollars per share)	$ 1.50	$ 1.99	$ 3.28	$ 1.81
Income per share, diluted (in dollars per share)	$ 1.48	$ 1.96	$ 3.26	$ 1.78