Variable Interest Entities - Assets and Liabilities of Funds that are VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets
Investments at fair value	$ 114.7	$ 303.8
Total assets	1,417.2	1,419.7
Liabilities
Total liabilities	1,145.8	1,221.3
Variable Interest Entity, Primary Beneficiary
Assets
Investments at fair value	0.0	119.5
Other assets of consolidated Funds	103.0	85.7
Assets of consolidated Funds held for sale	114.3	0.0
Total assets	217.3	205.2
Liabilities
Liabilities of consolidated Funds	0.0	6.2
Liabilities held for sale	0.1	0.0
Total liabilities	$ 0.1	$ 6.2