Stockholders' Equity - Summary of Changes in Stockholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Equity [Abstract]
Beginning Balance			$ 549,013
Net Income	$ 2,544	$ 14,395	5,861	$ 24,002
Dividend payments			(9,509)
Dividends accrued for unvested restricted stock units			10
Net unrealized losses on available-for-sale securities (net of tax)	(1,783)	1,219	(2,286)	298
Defined benefit plan adjustments	72		140
Foreign currency translation adjustment	872	$ 134	(2,446)	386
Proceeds from stock option exercises			833	$ 1,781
Purchase of treasury stock			(49,307)
Income tax benefit from exercise of stock options			(23)
Stock-based compensation expense			3,114
Ending Balance	$ 495,400		$ 495,400