Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit)	$ 55.0	$ 35.4	$ 95.6
Statutory federal tax rate	21.00%	21.00%	35.00%
Provisional tax expense			$ 22.6
Provisional tax expense previously recorded through AOCI			43.5
Provisional tax benefit recorded previously			20.9
Decrease in tax expense		$ 9.2
One-time transition tax liability			6.2
Decrease in income tax expense		2.4
Unrecognized tax benefits	$ 1.9	$ 2.6	$ 2.3
Accrued interest and penalties	0.4
State and Local Jurisdiction [Member]
Valuation allowance	0.1
Domestic Tax Authority [Member]
Valuation allowance	$ 0.4