Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Changes in accumulated other comprehensive income (loss), net of tax
Balance at the beginning of the period	$ (13,183)
Other comprehensive income (loss) before reclassifications	(4,455)
Amounts reclassified from accumulated other comprehensive gain	904
Other comprehensive (loss) gain, net of tax	(3,551)	1,774	(4,072)
Balance at the end of the period	(16,734)	(13,183)
Defined Benefit Pension Plan
Changes in accumulated other comprehensive income (loss), net of tax
Balance at the beginning of the period	(8,445)
Other comprehensive income (loss) before reclassifications	584
Amounts reclassified from accumulated other comprehensive gain	904
Other comprehensive (loss) gain, net of tax	1,488
Balance at the end of the period	(6,957)
Foreign Currency Translation Losses
Changes in accumulated other comprehensive income (loss), net of tax
Balance at the beginning of the period	(5,069)
Other comprehensive income (loss) before reclassifications	(4,789)
Other comprehensive (loss) gain, net of tax	(4,789)
Balance at the end of the period	(9,858)
Unrealized Gains and (Losses) on Available-for-Sale Securities
Changes in accumulated other comprehensive income (loss), net of tax
Balance at the beginning of the period	331
Other comprehensive income (loss) before reclassifications	(250)
Other comprehensive (loss) gain, net of tax	(250)
Balance at the end of the period	$ 81