Income Taxes (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 65.2	$ 62.3	$ 55.0
Additions for tax positions related to the current year	0.0	5.5	5.0
Additions for tax positions of prior years	1.0	0.0	2.5
Reductions for tax positions of prior years	(26.6)	(0.7)	(0.1)
Settlements	(7.1)	(1.9)	0.0
Expiration of statute of limitations	(4.3)	0.0	(0.1)
Ending balance	$ 28.2	$ 65.2	$ 62.3