Investments - Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 0.1	$ 0.3
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	38.9	35.9
Notes Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 4.9	$ 4.9
Minimum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Period Required For Considering Financing Receivable As Non Accrual Status	60 days
Period for placing financing receivables on non-accrual status	89 days
Past Due Period Of Financing Receivable Accruing Interest	90 days
Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Period Required For Considering Financing Receivable As Non Accrual Status	89 days