Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Balance, Beginning Balance	$ 226.9	$ 133.4	$ 127.1
Valuation Allowances and Reserves, Charged to Cost and Expense	(33.7)	(88.5)	(11.0)
Valuation Allowances and Reserves, Charged to Other Accounts	12.1	10.6	4.7
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	0.0	5.6	0.0
Valuation Allowances and Reserves, Balance, Ending Balance	181.1	226.9	133.4
SEC Schedule, 12-09, Allowance, Loan and Lease Loss, Real Estate [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Balance, Beginning Balance	9.4	7.7	6.8
Valuation Allowances and Reserves, Charged to Cost and Expense	(1.9)	(1.7)	(0.9)
Valuation Allowances and Reserves, Charged to Other Accounts	0.0	0.0	0.0
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	0.0	0.0	0.0
Valuation Allowances and Reserves, Balance, Ending Balance	$ 11.3	$ 9.4	$ 7.7