Related Parties Related Parties - Summary of Sub-allocation Assets (Details) - Apollo - Related Party - Sub-allocated assets [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Sub-allocation Assets	$ 182,691	$ 180,889
Percentage of Sub-allocation Assets	100.00%	100.00%
Core Sub-allocation Assets [Member]
Related Party Transaction [Line Items]
Sub-allocation Assets	$ 46,343	$ 49,392
Percentage of Sub-allocation Assets	25.40%	27.30%
Core Plus [Member]
Related Party Transaction [Line Items]
Sub-allocation Assets	$ 41,810	$ 41,516
Percentage of Sub-allocation Assets	22.90%	23.00%
Yield [Member]
Related Party Transaction [Line Items]
Sub-allocation Assets	$ 70,497	$ 64,693
Percentage of Sub-allocation Assets	38.50%	35.80%
High Alpha [Member]
Related Party Transaction [Line Items]
Sub-allocation Assets	$ 7,038	$ 6,200
Percentage of Sub-allocation Assets	3.90%	3.40%
Other Sub-allocation Assets [Member]
Related Party Transaction [Line Items]
Sub-allocation Assets	$ 17,003	$ 19,088
Percentage of Sub-allocation Assets	9.30%	10.50%