Accumulated Other Comprehensive Loss - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Amortization of defined benefit pension items:
Prior service benefit/cost	$ (6)	$ (6)
Amortization of actuarial loss	135	157
Total before tax	129	151
Income tax benefit	(46)	(55)
Amount reclassified out of accumulated other comprehensive loss	$ 83	$ 96