Subsequent Event - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		1 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jul. 17, 2014 Subsequent Event Dividend Declared
Subsequent Event [Line Items]
Dividends declared	$ 0.38	$ 0.36	$ 0.76	$ 0.72	$ 0.38
Dividend payable date					Sep. 19, 2014
Dividend payable, stockholders of record date					Aug. 27, 2014
Dividend announcement date					Jul. 17, 2014