Stock Repurchases - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands	6 Months Ended	9 Months Ended	11 Months Ended	12 Months Ended	29 Months Ended
	Jun. 30, 2015	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2014	Nov. 30, 2014	Aug. 31, 2012
Equity, Class of Treasury Stock [Line Items]
Stock repurchases program, remaining authorized repurchase amount		$ 4,900,000	$ 4,900,000
Total number of shares repurchased (in shares)		1,424		884
Dollar amount of shares repurchased		$ 50,020,000		$ 24,091,000
Average price paid per share (in dollars per share)		$ 35.13		$ 27.24
August 2012 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchases program, authorized amount							$ 50,000,000
Stock repurchases program, amount repurchased	$ 4,900,000				$ 45,100,000
November 2014 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchases program, authorized amount						$ 50,000,000
Stock repurchases program, amount repurchased			$ 45,100,000