Variable Interest Entities - Unconsolidated VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entities
Unconsolidated VIE assets	$ 1,417.2	$ 1,419.7
Unconsolidated VIE liabilities	1,145.8	1,221.3
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entities
Unconsolidated VIE assets	6,393.4	6,625.5
Unconsolidated VIE liabilities	4,260.1	4,320.6
Equity interests on the Condensed Consolidated Balance Sheets	12.8	17.5
Maximum risk of loss	$ 18.3	$ 23.9