Earnings per Share and Dividends per Share - Additional Information (Detail) - $ / shares	Sep. 10, 2015	Jun. 12, 2015	Mar. 09, 2015	Dec. 08, 2014
Weighted Average Amounts Used In Calculating Earnings Per Share [Line Items]
Dividend paid		$ 0.06	$ 0.06	$ 0.05
Date of record		May 20, 2015	Feb. 13, 2015	Nov. 14, 2014
Subsequent Event [Member]
Weighted Average Amounts Used In Calculating Earnings Per Share [Line Items]
Dividend paid	$ 0.06
Date of record	Aug. 18, 2015