Shareholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data	1 Months Ended	3 Months Ended			9 Months Ended
	Feb. 28, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2011
Stockholders Equity Note [Line Items]
Common stock repurchased					4,713,000
Common stock authorized to be repurchased, number of shares		20,000,000			20,000,000
Common stock authorized to be repurchased, expiration date		2013-02			2013-02
Cash dividend payment, frequency	quarterly
Common stock dividends, paid per share					$ 0.06
Common stock dividends, total cash paid					$ 28,686
Common stock dividends, payment date		Sep. 09, 2011	Jun. 10, 2011	Mar. 10, 2011
Common stock dividends, close of business date		Aug. 22, 2011	May 20, 2011	Feb. 22, 2011