Equity, Stock-based Comp Expense (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expense incurred for stock-based compensation plans					$ 49.7	$ 47.6	$ 44.2
Recognized tax benefit related to stock-based compensation					78.3	11.4	11.3
Income tax expense (benefit)					691.7	308.5	280.5
Selling, General and Administrative Expenses
Expense incurred for stock-based compensation plans					49.7	$ 47.6	$ 44.2
Impact of ASU 2016-09
Income tax expense (benefit)	$ (20.8)	$ (16.6)	$ (21.2)	$ (8.0)	$ (66.6)