Common Stock and Share-Based Compensation - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended			9 Months Ended		3 Months Ended		9 Months Ended
	Nov. 30, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Common Stock	Sep. 30, 2013 Common Stock	Sep. 30, 2014 Common Stock	Sep. 30, 2013 Common Stock
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
Cash dividends paid		$ 6,500,000	$ 6,500,000	$ 6,500,000	$ 19,654,000
Authorized amount for common share repurchase threshold									2,380,000,000.00
Repurchase of common stock (in shares)							0	0	1,727,275	0
Remaining authorized amount for common share repurchase									$ 275,000,000
Stock options granted					0	0