Accumulated Other Comprehensive Income - Components in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense (benefit)	$ 79	$ 59	$ 80	$ 111
Net income (loss)	413	171	2,419	326
Reclassifications, net of tax			7
Interest expense	$ 598	$ 114	1,077	$ 211
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of certain income tax effects			0
Reclassifications, net of tax			(1)
Reclassifications, before tax			(1)
Past service liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications, before tax			0
Actuarial losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications, before tax			(1)
Reclassification from AOCI | Unrealized gains on available-for-sale securities:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gain on AFS securities			0
Income tax expense (benefit)			0
Net income (loss)			0
Reclassification from AOCI | Unrealized gains on cash flow hedges:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense (benefit)			(4)
Net income (loss)			8
Interest expense			$ 12