Earnings Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 18, 2011
Equity, Class of Treasury Stock [Line Items]
Total Number of Shares Repurchased	860,000	630,000	341,000
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	4,900,000