Earnings Per Share - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended				9 Months Ended	0 Months Ended	9 Months Ended		0 Months Ended			9 Months Ended	0 Months Ended		0 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jul. 14, 2014	Feb. 25, 2014	Sep. 30, 2014 Common Stock	Feb. 03, 2014 Merrill Lynch Accelerated Share Repurchase Agreement	Sep. 30, 2014 Merrill Lynch Accelerated Share Repurchase Agreement	Feb. 03, 2014 Merrill Lynch Accelerated Share Repurchase Agreement tranche	Feb. 03, 2014 Merrill Lynch Accelerated Share Repurchase Agreement Initial Delivery	Feb. 03, 2014 Merrill Lynch Accelerated Share Repurchase Agreement Fair Market Value	Apr. 30, 2014 Merrill Lynch Accelerated Share Repurchase Agreement Final Settlement	Sep. 30, 2014 Merrill Lynch Accelerated Share Repurchase Agreement Total	Apr. 30, 2014 JP Morgan Accelerated Share Repurchase Agreement	Apr. 30, 2014 JP Morgan Accelerated Share Repurchase Agreement tranche	May 01, 2014 JP Morgan Accelerated Share Repurchase Agreement Initial Delivery	May 01, 2014 JP Morgan Accelerated Share Repurchase Agreement Fair Market Value	Jul. 15, 2014 JP Morgan Accelerated Share Repurchase Agreement Final Settlement	Oct. 14, 2014 Subsequent Event
Earnings Per Share Disclosure [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	$ 79,473,000	$ 89,981,000	$ 220,297,000	$ 252,244,000
Increase in dividend rate, percentage						15.00%
Cash dividend, amount per share (in dollars per share)					$ 0.275	$ 0.275														$ 0.275
Stock Repurchase Program, Authorized Amount								50,000,000							100,000,000
Number of tranches										2						2
Authorized amount per tranche purchased								25,000,000							50,000,000
Payment for repurchase of common stock			150,000,000	582,298,000							50,000,000						100,000,000
Repurchase of common stock shares (in shares)											623,248		150,504	773,752			1,193,317		223,000
Share price minimum for repurchase agreement transaction (in dollars per share)																$ 33.50
Shares repurchased												$ 40,000,000						$ 80,000,000
Forward Purchase Price adjustment amount (in dollars per share)									$ 0.77
Shares repurchased (in shares)							1,967,069
Shares available for repurchase (in shares)	3,972,525		3,972,525