Other Comprehensive Income (Loss) - Related Tax Effects Allocated to Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Equity [Abstract]
Retirement benefits adjustment, before tax amount	$ (1,418)	$ 159	$ (1,585)	$ 252
Cumulative translation adjustment, before tax amount	(713)	163	(408)	(2,845)
Total other comprehensive income (loss), before tax amount	(2,131)	322	(1,993)	(2,593)
Retirement benefits adjustment, tax	275	(33)	551	(66)
Cumulative translation adjustment, tax	0	0	0	0
Total other comprehensive income (loss), tax	275	(33)	551	(66)
Retirement benefits adjustment, after tax amount	(1,143)	126	(1,034)	186
Cumulative translation adjustment, after tax amount	(713)	163	(408)	(2,845)
Total other comprehensive income (loss)	$ (1,856)	$ 289	$ (1,442)	$ (2,659)