Stock Repurchase Plan - Additional Information (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended	9 Months Ended	1 Months Ended
	Sep. 30, 2014 2014 Repurchase Plan	Jun. 30, 2014 2014 Repurchase Plan	Sep. 30, 2014 2014 Repurchase Plan	Jul. 31, 2013 2013 Repurchase Plan	Dec. 31, 2012 2012 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Additional authorized amount of outstanding common stock to be repurchased		$ 150
Authorized amount to repurchase outstanding common stock				150	50
Aggregate shares repurchased			3,993,401		1,573,588
Common stock, shares repurchase value			160.0
Remaining amount of authorized under 2014 Repurchase Plan	$ 100