Investments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Trading Securities
Amortized Cost
Amortized Cost	$ 20.4	$ 17.2
Gross Unrealized Gains and Losses
Gross Unrealized Gains	0.5	0.9
Gross Unrealized Losses	0.1	0.1
Fair Value (Net Carrying Amount)
Fair Value (Net Carrying Amount)	20.8	18.0
Trading equity securities
Amortized Cost
Amortized Cost	7.8	6.4
Gross Unrealized Gains and Losses
Gross Unrealized Gains	0.4	0.6
Gross Unrealized Losses	0.0	0.0
Fair Value (Net Carrying Amount)
Fair Value (Net Carrying Amount)	8.2	7.0
Trading debt securities
Amortized Cost
Amortized Cost	12.6	10.8
Gross Unrealized Gains and Losses
Gross Unrealized Gains	0.1	0.3
Gross Unrealized Losses	0.1	0.1
Fair Value (Net Carrying Amount)
Fair Value (Net Carrying Amount)	$ 12.6	$ 11.0

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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