Investments in Qualified Affordable Housing Projects and Historic Projects - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Remaining unfunded equity contributions	$ 109.4		$ 107.4
Qualified Affordable Housing Projects
Schedule of Equity Method Investments [Line Items]
Amortization expense	5.9	$ 5.3
Tax credits and other benefits	7.9	6.6
Remaining investment amount	222.1		214.3
Federal Historical Projects and Ohio Historical Preservation Projects
Schedule of Equity Method Investments [Line Items]
Remaining investment amount	50.2		$ 48.6
Federal Historical Projects
Schedule of Equity Method Investments [Line Items]
Amortization expense	0.5	0.2
Tax credits and other benefits	$ 0.6	0.3
State Tax Credits
Schedule of Equity Method Investments [Line Items]
Amortization expense		$ 0.4