Derivatives and Hedging Activities - Effect of Fair Value and Cash Flow Hedges on Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense — Long-term debt		$ 49	$ 60
Interest income — Loans		837	889
Interest Income - securities		173	130
Investment banking and debt placement fees		163	162
Deposits		14	21
Other income	[1]	(4)	51
Net gain (loss) on cash flow hedging relationships
Net Gains (Losses) Reclassified From OCI Into Income		65	89
Interest rate | Interest expense – long-term debt | Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items		240	204
Recognized on derivatives designated as hedging instruments		(216)	(166)
Net income (expense) recognized on fair value hedges		24	38
Interest rate | Interest expense – long-term debt | Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		(1)	(1)
Net income (expense) recognized on cash flow hedges		(1)	(1)
Interest rate | Interest income – loans | Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items		0	0
Recognized on derivatives designated as hedging instruments		0	0
Net income (expense) recognized on fair value hedges		0	0
Interest rate | Interest income – loans | Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		64	89
Net Gains (Losses) Reclassified From OCI Into Income		64	89
Net income (expense) recognized on cash flow hedges		64	89
Interest rate | Interest Income - securities | Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items		(276)	(266)
Recognized on derivatives designated as hedging instruments		282	267
Net income (expense) recognized on fair value hedges		6	1
Interest rate | Interest Income - securities | Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		0	0
Net income (expense) recognized on cash flow hedges		0	0
Interest rate | Investment banking and debt placement fees | Fair Value Hedging
Net gains (losses) on fair value hedging relationships
Recognized on hedged items		0	0
Recognized on derivatives designated as hedging instruments		0	0
Net income (expense) recognized on fair value hedges		0	0
Interest rate | Investment banking and debt placement fees | Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Net income (expense) recognized on cash flow hedges		2	1
Interest rate | Investment banking and debt placement fees | Cash Flow Hedging
Net gain (loss) on cash flow hedging relationships
Net Gains (Losses) Reclassified From OCI Into Income		$ 2	$ 1

[1] For the three months ended March 31, 2022, and March 31, 2021, we had no net securities gains (losses). For the three months ended March 31, 2022, and March 31, 2021, we did not have any impairment losses related to securities.