Earnings Per Share - Additional Information (Detail) (USD $)	9 Months Ended				9 Months Ended		0 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Jul. 10, 2013	Feb. 12, 2013	Sep. 30, 2013 Common Stock	Sep. 30, 2013 J P Morgan Securities LLC Accelerated Share Repurchase Agreement	May 10, 2013 J P Morgan Securities LLC Accelerated Share Repurchase Agreement Initial Delivery	May 10, 2013 J P Morgan Securities LLC Accelerated Share Repurchase Agreement Fair Market Value	Sep. 30, 2013 J P Morgan Securities LLC Accelerated Share Repurchase Agreement Final Settlement	Feb. 12, 2013 Maximum	Oct. 07, 2013 Subsequent Event
Earnings Per Share Disclosure [Line Items]
Increase in dividend rate, percentage				20.00%
Cash dividend, amount per share (in dollars per share)			$ 0.24	$ 0.24							$ 0.24
Stock repurchase program, number of shares authorized to be repurchased (in shares)										15,000,000
Payment for repurchase of common stock	$ 582,298,000	$ 40,470,000					$ 450,000,000
Repurchase of common stock shares (in shares)							5,680,921		1,500,000
Shares repurchased								360,000,000
Forward Purchase Prices adjustment amount (in dollars per share)						$ 1.01
Shares repurchased (in shares)					7,814,045
Shares available for repurchase (in shares)	7,185,955