Other Assets - Capital Contributions Made to Loan Origination Partners (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($) investment	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Other Assets [Line Items]
Equity method investments	$ 30.4		$ 30.4
Unrealized loss on loan originator investment	2.0		13.4
Loan Origination Partners
Other Assets [Line Items]
Impairment on investment		$ 0.0	28.6	$ 0.0
Impaired investment
Other Assets [Line Items]
Equity method investments	0.0		0.0
Preferred Equity Investments
Other Assets [Line Items]
Impairment reversal		$ 10.0
Number of investments repaid | investment		2
Common Stock | Loan Origination Partners
Other Assets [Line Items]
Equity method investments	6.8		6.8
Preferred Stock | Loan Origination Partners
Other Assets [Line Items]
Equity method investments	$ 23.5		$ 23.5