Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 8,545	$ 11,488	$ 6,606	$ 16,376
Changes in fair value of derivative, net of tax of $37 and $74	0	59	0	118
Changes in defined benefit pension plans, net of tax of $433, $401, $866, and $801	695	640	1,390	1,282
Other	(16)	(7)	(32)	(14)
Total comprehensive income	$ 9,224	$ 12,180	$ 7,964	$ 17,762