Earnings Per Share and Equity (Schedule of Share Repurchase Program) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Number of repurchased shares	16,800,000	1,600,000	0
Beginning accrued share repurchases	$ 0.0	$ 0.0	$ 0.0
Aggregate purchase price	315.0	25.0	0.0
Fees, commissions and other expenses	0.3	0.0	0.0
Less: ending accrued share repurchases	0.0	0.0	0.0
Total cash used for share repurchases	$ 315.3	$ 25.0	$ 0.0
Weighted-average purchase price per share (in dollars per share)	$ 18.78	$ 15.35	$ 0.00
Available for future purchases at period end	$ 1,500.0	$ 603.2	$ 628.2
Treasury shares reissued or retired	0