Variable Interest Entities - Assets and Liabilities of Funds that are VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets
Investments at fair value	$ 266.2	$ 303.8
Total assets	1,423.5	1,419.7
Liabilities
Total liabilities	1,229.7	1,221.3
Variable Interest Entity, Primary Beneficiary
Assets
Investments at fair value	107.6	119.5
Other assets of consolidated Funds	87.3	85.7
Total assets	194.9	205.2
Liabilities
Other liabilities	9.9	6.2
Total liabilities	$ 9.9	$ 6.2