Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Comprehensive Income
Net income (loss)	$ (4,172)	$ 5,637	$ (2,558)	$ 7,482	$ 23,991
Other comprehensive income (loss):
Adjustment to pension liability	1,557	840	2,902	1,760
Tax expense	(623)	(336)	(1,161)	(704)
Adjustment to pension liability, net of tax	934	504	1,741	1,056
Foreign currency translation adjustment	1,386	420	(101)	607
Total other comprehensive income (loss), net of tax	2,320	924	1,640	1,663
Comprehensive income (loss)	(1,852)	6,561	(918)	9,145
Accumulated other comprehensive income
Balance at beginning of period			(47,229)	(28,118)	(28,118)
Other comprehensive income (loss), net of tax, before reclassifications			(101)	607
Amounts reclassified from accumulated other comprehensive income, net of tax			1,741	1,056
Net current period other comprehensive income (loss), net of tax			1,640	1,663	(19,111)
Balance at end of period	(45,589)	(26,455)	(45,589)	(26,455)	(47,229)
Defined Benefit Pension Items
Accumulated other comprehensive income
Balance at beginning of period			(49,560)	(32,279)	(32,279)
Amounts reclassified from accumulated other comprehensive income, net of tax			1,741	1,056
Net current period other comprehensive income (loss), net of tax			1,741	1,056
Balance at end of period	(47,819)	(31,223)	(47,819)	(31,223)	(49,560)
Foreign Currency Items
Accumulated other comprehensive income
Balance at beginning of period			2,331	4,161	4,161
Other comprehensive income (loss), net of tax, before reclassifications			(101)	607
Net current period other comprehensive income (loss), net of tax			(101)	607
Balance at end of period	$ 2,230	$ 4,768	$ 2,230	$ 4,768	$ 2,331