Common Stock and Share-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended				9 Months Ended
	Nov. 30, 2013	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Quarterly dividends expected (in dollars per share)	$ 0.07
Annual dividends expected (in dollars per share)	$ 0.28
Dividends paid (in dollars per share)		$ 0.07	$ 0.07	$ 0.07	$ 0.07
Cash dividends paid						$ (19,784,000)	$ (19,654,000)
Preferred stock authorized		1,000,000				1,000,000
Common stock authorized		250,000,000				250,000,000
Common stock, par value (in dollars per share)		$ 0.01				$ 0.01		$ 0.01
Preferred stock, par value (in dollars per share)		$ 0.01				$ 0.01
Common stock repurchase						$ 53,010,000	$ 25,000,000
Stock options granted						0	0
Decrease in deferred tax assets		$ 1,700,000				$ 1,700,000
Decrease to additional paid in capital		1,700,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized amount for common share repurchase threshold		2,380,000,000.00				$ 2,380,000,000.00
Repurchase of common stock (in shares)						(3,165,582)	(1,727,275)
Remaining authorized amount for common share repurchase		$ 222,100,000				$ 222,100,000
DEUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend equivalent units issued						$ 225,000