Stock Repurchases - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands	1 Months Ended				3 Months Ended	12 Months Ended			29 Months Ended
	Sep. 30, 2015	Aug. 31, 2015	Jun. 30, 2015	May. 31, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Nov. 30, 2014	Aug. 31, 2012
Equity, Class of Treasury Stock [Line Items]
Total number of shares repurchased	554	189	360	321		1,424	884	885
Dollar amount of shares repurchased	$ 18,622,000	$ 6,378,000	$ 13,493,000	$ 11,528,000		$ 50,021,000	$ 24,091,000	$ 20,962,000
Average price paid per share	$ 33.61	$ 33.75	$ 37.48	$ 35.91		$ 35.13	$ 27.24	$ 23.70
August 2012 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchases program, authorized amount											$ 50,000,000.0
Stock repurchases program, amount repurchased					$ 4,900,000				$ 45,100,000
November 2014 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchases program, authorized amount										$ 50,000,000
Stock repurchases program, amount repurchased									$ 45,100,000
Stock repurchase program, remaining authorized repurchase amount						$ 4,900,000