Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stockholders Equity [Line Items]
Dividends payable, date declared	May 21, 2014	Feb. 20, 2014
Dividends payable, date of record	Jun. 06, 2014	Mar. 07, 2014
Dividends per share	$ 0.125	$ 0.125	$ 0.125	$ 0.125	$ 0.250	$ 0.125
Dividend paid					$ 12.0	$ 6.0
Approved amount for open market repurchase of common stock					100.0
Number of stock purchased under open market					0	0
Available amount for open market repurchases under plan					$ 90.8