Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Examination [Line Items]
Income tax expense at U.S. federal rate									$ 41.5	$ 48.5	$ 63.0
Income tax expense at U.S. federal rate, percent									21.00%	21.00%	35.00%
State income taxes, net of federal income tax benefit									$ 7.5	$ 7.4	$ 3.0
State income taxes, net of federal income tax benefit, percent									3.80%	3.20%	1.70%
Impacts of Tax Reform Act									$ 0.0	$ (2.3)	$ (10.6)
Impacts of Tax Reform Act, percent									0	(0.010)	(0.059)
Stock-based compensation activity									$ (2.2)	$ (2.6)	$ 0.3
Stock-based compensation activity, percent									(1.10%)	(1.10%)	0.20%
Equity in net income of unconsolidated subsidiaries (including holding gains upon acquisition)									$ 0.3	$ 1.0	$ 1.2
Holding gain upon acquisition of additional ownership of equity method investments, percent									0.20%	0.40%	0.70%
Book gain over tax gain on sale of HelloWallet									$ 0.0	$ 0.0	$ (6.8)
Book gain over tax gain on sale of HelloWallet, percent									0.00%	0.00%	(3.80%)
Net change in valuation allowance related to non-U.S. deffered tax assets, primarily net operating losses									$ (2.1)	$ (0.2)	$ 0.1
Net change in valuation allowance related to non-U.S. deffered tax assets, primarily net operating losses, percent									(1.10%)	(0.10%)	0.10%
Difference between U.S. federal statutory and foreign tax rates									$ 1.1	$ 0.2	$ (5.2)
Difference between U.S. federal statutory and foreign tax rates, percent									0.60%	0.10%	(2.90%)
Foreign tax provisions (GILTI, FDII, and BEAT)									$ (1.4)	$ (3.7)	$ 0.0
Foreign tax provisions (GILTI, FDII, and BEAT), percent									(0.70%)	(1.60%)	0.00%
Change in unrecognized tax benefits									$ (0.9)	$ 1.0	$ 1.2
Changes in unrecognized tax benefits, percent									(0.50%)	0.40%	0.70%
Other tax credits									$ (2.2)	$ (3.6)	$ (3.7)
Other tax credits, percent									(1.10%)	(1.60%)	(2.10%)
Other - net									$ 4.0	$ 2.1	$ 0.4
Other - net, percent									2.00%	0.90%	0.20%
Income tax expense	$ 9.1	$ 13.3	$ 11.7	$ 11.5	$ 5.5	$ 16.1	$ 12.8	$ 13.4	$ 45.6	$ 47.8	$ 42.9
Income tax expense, percent									23.10%	20.70%	23.90%