Basis of Presentation Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncement, Early Adoption [Line Items]
Income tax excess tax benefit adjustment - ASU 2016-09 Adoption	$ 8.3	$ 2.3
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options		$ 2.5
Basic (in dollars per share)	$ 3.03	$ 1.13
Diluted (in dollars per share)	$ 2.86	1.08
EPS [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Basic (in dollars per share)		0.99
Diluted (in dollars per share)		$ 0.96
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment		314,000