Income Taxes (Contingencies and Tax Reform) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	$ 6.4	$ 5.8	$ 5.6	$ 4.9
Additions based on tax positions related to the current year		0.0	0.0	0.0
Additions for tax positions of prior years		0.8	0.8	0.7
Reductions for tax positions of prior years		0.0	(0.4)	0.0
Reductions for expirations of statute of limitations		(0.2)	(0.2)	0.0
Settlements		0.0	0.0	0.0
Balance at December 31		6.4	5.8	5.6
Unrecognized tax benefits, accumulated interest and penalties		6.8	6.1	5.5
Deferred tax assets related to unrecognized tax benefits		2.8	4.2	4.0
Net unrecognized tax benefits, associated interest, penalties and deferred tax asset that if resolved would impact effective tax rate		10.4	7.7	7.1
Recognized interest and penalties		$ 0.4	$ 0.4	$ 0.4
Subsequent Event [Line Items]
Income tax provision at statutory rate, %		35.00%	35.00%	35.00%
Impact of enactment of new tax legislation, amount		$ 41.3
Impact of enactment of new tax legislation, effective tax rate		6.50%
Subsequent Event [Member]
Subsequent Event [Line Items]
Income tax provision at statutory rate, %	21.00%