Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income (loss)	$ (170,914)	$ 6,420	$ (173,473)	$ 13,902	$ 23,991
Other comprehensive income (loss):
Adjustment to pension liability	1,557	930	4,459	2,691
Tax expense	(623)	(372)	(1,784)	(1,076)
Adjustment to pension liability, net of tax	934	558	2,675	1,615
Foreign currency translation adjustment	(1,077)	(1,348)	(1,178)	(742)
Total other comprehensive loss, net of tax	(143)	(790)	1,497	873
Comprehensive income (loss)	(171,057)	5,630	(171,976)	14,775
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			(47,229)	(28,118)	(28,118)
Other comprehensive income (loss), net of tax, before reclassifications			(1,178)	(742)
Amounts reclassified from accumulated other comprehensive income, net of tax			2,675	1,615
Net current period other comprehensive income (loss), net of tax			1,497	873	(19,111)
Balance at end of period	(45,732)	(27,245)	(45,732)	(27,245)	(47,229)
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			(49,560)	(32,279)	(32,279)
Other comprehensive income (loss), net of tax, before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income, net of tax			2,675	1,615
Net current period other comprehensive income (loss), net of tax			2,675	1,615
Balance at end of period	(46,885)	(30,664)	(46,885)	(30,664)	(49,560)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period			2,331	4,161	4,161
Other comprehensive income (loss), net of tax, before reclassifications			(1,178)	(742)
Amounts reclassified from accumulated other comprehensive income, net of tax			0	0
Net current period other comprehensive income (loss), net of tax			(1,178)	(742)
Balance at end of period	$ 1,153	$ 3,419	$ 1,153	$ 3,419	$ 2,331