Common Stock Repurchased (Parenthetical) (Detail) (USD $) In Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2011		Mar. 31, 2011	Jun. 30, 2011
Equity, Class of Treasury Stock [Line Items]
Common Stock Repurchased - Amount	$ 70,000	[1]	$ 54,400	$ 124,364
Repurchase of Equity
Equity, Class of Treasury Stock [Line Items]
Common Stock Repurchased - Amount	$ 1,300

[1] Approximately $1.3 million of common stock repurchased during the three months ended June 30, 2011 was paid in July 2011.