Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Amortization of actuarial (loss) gain, tax	$ 283	$ 330	$ 156
Actuarial gain (loss) arising during the period, tax expense (benefit)	(413)	300	(1,810)
Unrealized gain (loss) on cash flow hedges, tax	$ 180	$ 0	$ 0