Basis of Presentation Stock Repurchase Program (Details) - USD ($)	1 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014
Accelerated Share Repurchases [Line Items]
Repurchase of common stock (in shares)		1,148,410
Repurchase of common stock		$ 47,144,000	$ 2,981,000
Average cost per share for repurchase of common stock (in USD per share)		$ 34.42
Treasury Stock
Accelerated Share Repurchases [Line Items]
Repurchase of common stock		$ 39,529,000	$ 2,981,000
Additional Paid-in Capital
Accelerated Share Repurchases [Line Items]
Repurchase of common stock		7,615,000
2015 Stock Repurchase Program
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount	$ 50,000,000	$ 50,000,000
Stock repurchase program, expiration date		Dec. 31, 2015
Repurchase of common stock (in shares)	498,700
Initial delivery as a percent of total shares expected to be delivered under ASR	70.00%
Payment made under accelerated share repurchase	$ 25,000,000	$ 25,000,000
2015 Stock Repurchase Program | Treasury Stock
Accelerated Share Repurchases [Line Items]
Repurchase of common stock	17,400,000
2015 Stock Repurchase Program | Additional Paid-in Capital
Accelerated Share Repurchases [Line Items]
Repurchase of common stock	$ 7,600,000