Loans and Allowance for Credit Losses - Activity in the Allowance for Credit Losses for Loans Held for Investment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 122
Provision	(9)	$ 36
Ending balance	118
Leveraged Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	97	61
Charge-offs	0	(5)
Provision	(1)	27
Currency translation	4
Ending balance	92	83
Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	17	10
Charge-offs	0	0
Provision	(5)	0
Currency translation	0
Ending balance	12	10
Other Loans | Fund Finance
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	10
Other Loans | Other Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	2
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	8	2
Charge-offs	0	0
Provision	6	2
Currency translation	0
Ending balance	14	4
Held-to-Maturity Securities
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3	0
Charge-offs	0	0
Provision	(1)	4
Currency translation	0
Ending balance	2	4
Off Balance Sheet Commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	22	19
Charge-offs	0	0
Provision	(7)	3
Currency translation	0
Ending balance	15	22
All Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1	1
Charge-offs	0	0
Provision	(1)	0
Currency translation	0
Ending balance	0	1
Total Credit Reserve
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	148	93
Charge-offs	0	(5)
Provision	(9)	36
Currency translation	4
Ending balance	$ 135	$ 124