Earnings Per Share - Additional Information (Detail) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Aug. 18, 2011
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Repurchased	279,000	500,000	130,000
2011 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Maximum amount of shares authorized for repurchase				5,000,000
Total Number of Shares Repurchased		4,500,000