Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accounts payable and accrued purchases	$ 914.6	$ 911.9
Accrued employee compensation and benefits payable	571.4	574.8
Accrued rebates	1,612.7	1,431.3
Accrued sales returns	175.7	118.4
Other accrued expenses	910.1	1,276.0
Accounts payable and accrued expenses, total	$ 4,184.5	$ 4,312.4