Stock Repurchase Program - Additional Information (Detail) (USD $)	1 Months Ended
Nov. 30, 2011	Apr. 30, 2008	Mar. 31, 2013
Equity [Line Items]
Repurchase of authorized common stock	$ 80,000,000	$ 50,000,000
Repurchase of shares			1,375,875
Repurchase of shares, Value			$ 30,000,000

The amount authorized by an entity's Board of Directors under a stock repurchase plan.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration