Other Comprehensive Income (Loss) - Related Tax Effects Allocated to Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
Retirement benefits adjustment, before tax amount	$ (893)	$ 159	$ (2,478)	$ 411
Cumulative translation adjustment, before tax amount	621	(2,191)	215	(5,036)
Total other comprehensive income (loss), before tax amount	(272)	(2,032)	(2,263)	(4,625)
Retirement benefits adjustment, tax	228	(33)	779	(99)
Cumulative translation adjustment, tax	0	0	0	0
Total other comprehensive income (loss), tax	228	(33)	779	(99)
Retirement benefits adjustment, after tax amount	(665)	126	(1,699)	312
Cumulative translation adjustment, after tax amount	621	(2,191)	215	(5,036)
Total other comprehensive income (loss)	$ (44)	$ (2,065)	$ (1,484)	$ (4,724)