Segment Reporting - Segment Result and Reconciliations to GAAP - Core Earnings Adjustments (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (loss) after provisions for loan losses	$ 321	$ 450
Total other income (loss)	223	304
Goodwill and acquired intangible asset impairment and amortization	4	5
Income tax expense (benefit)	77	114
Net income	255	370
Total Adjustments [Member] | Adjustments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (loss) after provisions for loan losses	61	68
Total other income (loss)	98	23
Goodwill and acquired intangible asset impairment and amortization	4	5
Total Core Earnings adjustments to GAAP	155	86
Income tax expense (benefit)	35	21
Net income	120	65
Net Impact of Goodwill and Acquired Intangible Assets [Member] | Total Adjustments [Member] | Adjustments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Goodwill and acquired intangible asset impairment and amortization	4	5
Total Core Earnings adjustments to GAAP	(4)	(5)
Net Impact of Derivative Accounting [Member] | Total Adjustments [Member] | Adjustments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (loss) after provisions for loan losses	61	68
Total other income (loss)	98	23
Total Core Earnings adjustments to GAAP	$ 159	$ 91