Treasury Stock (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Treasury stock purchase plan	$ 40.0
Treasury stock purchase plan remaining available	$ 22.5
Stock Repurchased and Retired During Period, Shares		5,600,000
Shares Paid for Tax Withholding for Share Based Compensation	17,299	4,232
Payments Related to Tax Withholding for Share-based Compensation	$ 1.5	$ 0.2
Shares withheld for option exercise in lieu of cash payment	823	4,583
Value of option exercises with shares remitted to the company in lieu of cash payment	$ 0.1	$ 0.3