Stockholders' Equity - Summary of Changes in Stockholders' Equity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Equity [Abstract]
Beginning balance	$ 604,606
Net income	9,607	7,890
Dividend payments	(5,102)
Dividends accrued for unvested restricted stock units	6
Net unrealized gains (losses) on available-for-sale securities (net of tax)	(921)	(1,644)
Foreign currency translation adjustment	252	323
Proceeds from stock option exercises	1,541	55
Purchase of treasury stock	(9,427)
Income tax benefit from exercise of stock options	57
Stock-based compensation expense	2,057	2,232
Ending balance	$ 602,676