Segment Reporting - Segment Result and Reconciliations to GAAP - Core Earnings Adjustments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (loss) after provisions for loan losses	$ 739	$ 1,042	$ 1,393
Goodwill and acquired intangible asset impairment and amortization	10	19	30
Income tax expense (benefit)	85	182	219
Net income	228	645	717
Total Adjustments [Member] | Adjustments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (loss) after provisions for loan losses	84	(95)	(184)
Total other income (loss)	(11)	(171)	(51)
Goodwill and acquired intangible asset impairment and amortization	(10)	(19)	(30)
Total Core Earnings adjustments to GAAP	83	(247)	(205)
Income tax expense (benefit)	8	(60)	(39)
Net income	75	(187)	(166)
Net Impact of Goodwill and Acquired Intangible Assets [Member] | Total Adjustments [Member] | Adjustments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (loss) after provisions for loan losses	0	0	0
Total other income (loss)	0	0	0
Goodwill and acquired intangible asset impairment and amortization	(10)	(19)	(30)
Total Core Earnings adjustments to GAAP	10	19	30
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	84	(95)	(184)
Total other income (loss)	(11)	(171)	(51)
Goodwill and acquired intangible asset impairment and amortization	0	0	0
Total Core Earnings adjustments to GAAP	$ 73	$ (266)	$ (235)