Stockholder's Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	6 Months Ended		1 Months Ended
	Mar. 01, 2014	Jun. 30, 2014	Mar. 01, 2014	Dec. 10, 2012 Board of Directors Maximum
Schedule Of Stockholders Equity [Line Items]
Common stock repurchase authorized amount				$ 50
Common stock repurchased, shares		552,806
Common stock repurchased, value		14.0
Remaining authorized shares available for future repurchases		24.3
Sale of preferred stock			2,587,400
Convertible preferred stock dividend, rate	6.25%
Conversion rate of preferred stock			6,912,756
Convertible preferred stock, conversion date	Mar. 01, 2014
Annualized dividend on mandatory convertible preferred stock		$ 16.2