Investments - Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 42.5	$ 38.9
Notes Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 3.5	$ 4.9
Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due Period Of Financing Receivable Accruing Interest	90 days