Changes in Stockholders' Equity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Stockholders' Equity [Line Items]
Balance as of December 31, 2011			$ 126,816
Net income	15,787	15,351	43,557	39,182
Common stock issued from treasury stock			3,832
Common stock repurchased			(50,025)
Common stock repurchased, shares outstanding	0		(1,372,853)
Excess tax benefits from share-based awards			775
Non-cash share-based compensation			6,779
Dividends declared			(7,951)
Other comprehensive income	570	(11)	939	452
Balance as of September 30, 2012	124,722		124,722
Common Stock
Stockholders' Equity [Line Items]
Balance as of December 31, 2011			16,169
Balance as of December 31, 2011, shares outstanding			27,290,000
Common stock issued from treasury stock, shares outstanding			243,000
Common stock repurchased, shares outstanding			(1,373)
Balance as of September 30, 2012	16,169		16,169
Balance as of September 30, 2012, shares outstanding	26,160,000		26,160,000
Treasury Stock
Stockholders' Equity [Line Items]
Balance as of December 31, 2011			(2,524)
Common stock issued from treasury stock			121
Common stock repurchased			(686)
Balance as of September 30, 2012	(3,089)		(3,089)
Retained Earnings
Stockholders' Equity [Line Items]
Balance as of December 31, 2011			128,772
Net income			43,557
Common stock issued from treasury stock			3,711
Common stock repurchased			(49,339)
Excess tax benefits from share-based awards			775
Non-cash share-based compensation			6,779
Dividends declared			(7,951)
Balance as of September 30, 2012	126,304		126,304
Accumulated Other Comprehensive Loss
Stockholders' Equity [Line Items]
Balance as of December 31, 2011			(15,601)
Other comprehensive income			939
Balance as of September 30, 2012	$ (14,662)		$ (14,662)