Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 67,235	$ (82,477)	$ 10,529
Changes in fair value of derivative, net of tax of $142, $148 and $145	242	237	239
Changes in defined benefit pension plans, net of tax of $(2,455), $21,139, and $(27,516)	(3,936)	33,825	(45,500)
Other	149	253	(259)
Total comprehensive income (loss)	$ 63,690	$ (48,162)	$ (34,991)