CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at Cost	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020		2,000,000	427,000,000
Beginning balance at Dec. 31, 2020	$ 22,673	$ 1,965	$ 6	$ 18,940	$ 6,445	$ (4,623)	$ (60)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(502)				(502)
Dividends to preferred stockholders	(81)				(81)
Preferred stock issued	296	296
Preferred stock redemption	(250)	$ (247)			(3)
Treasury stock purchased (in shares)			(2,000,000)
Treasury stock purchased	(95)					(95)
Share-based compensation plans (in shares)			1,000,000
Share-based compensation plans	24			24
Employee stock purchase plan	17			17
Total comprehensive income (loss):
Net income	1,789				1,789
Other comprehensive income (loss)	(448)						(448)
Total comprehensive income (loss)	1,341				1,789		(448)
Ending balance (in shares) at Sep. 30, 2021		2,000,000	426,000,000
Ending balance at Sep. 30, 2021	23,423	$ 2,014	$ 6	18,981	7,648	(4,718)	(508)
Beginning balance (in shares) at Jun. 30, 2021		2,000,000	426,000,000
Beginning balance at Jun. 30, 2021	23,199	$ 2,014	$ 6	18,964	7,314	(4,718)	(381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(167)				(167)
Dividends to preferred stockholders	(26)				(26)
Preferred stock redemption	(3)				(3)
Share-based compensation plans	11			11
Employee stock purchase plan	6			6
Total comprehensive income (loss):
Net income	530				530
Other comprehensive income (loss)	(127)						(127)
Total comprehensive income (loss)	403				530		(127)
Ending balance (in shares) at Sep. 30, 2021		2,000,000	426,000,000
Ending balance at Sep. 30, 2021	23,423	$ 2,014	$ 6	18,981	7,648	(4,718)	(508)
Beginning balance (in shares) at Dec. 31, 2021		2,000,000	422,000,000
Beginning balance at Dec. 31, 2021	23,420	$ 2,014	$ 6	19,005	7,978	(4,918)	(665)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(569)				(569)
Dividends to preferred stockholders	(81)				(81)
Issuance of common stock - business acquisition (in shares)			72,000,000
Issuance of common stock - business acquisition	$ 3,036			3,036
Treasury stock purchased (in shares)	(77,543)
Treasury stock purchased	$ (2)					(2)
Share-based compensation plans (in shares)			2,000,000
Share-based compensation plans	61			61
Employee stock purchase plan (in shares)			0
Employee stock purchase plan	19			19
Total comprehensive income (loss):
Net income	1,420				1,420
Other comprehensive income (loss)	(4,158)						(4,158)
Total comprehensive income (loss)	(2,738)				1,420		(4,158)
Ending balance (in shares) at Sep. 30, 2022		2,000,000	496,000,000
Ending balance at Sep. 30, 2022	23,146	$ 2,014	$ 6	22,121	8,748	(4,920)	(4,823)
Beginning balance (in shares) at Jun. 30, 2022		2,000,000	496,000,000
Beginning balance at Jun. 30, 2022	24,328	$ 2,014	$ 6	22,100	8,346	(4,920)	(3,218)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(209)				(209)
Dividends to preferred stockholders	(25)				(25)
Share-based compensation plans (in shares)			0
Share-based compensation plans	15			15
Employee stock purchase plan (in shares)			0
Employee stock purchase plan	6			6
Total comprehensive income (loss):
Net income	636				636
Other comprehensive income (loss)	(1,605)						(1,605)
Total comprehensive income (loss)	(969)				636		(1,605)
Ending balance (in shares) at Sep. 30, 2022		2,000,000	496,000,000
Ending balance at Sep. 30, 2022	$ 23,146	$ 2,014	$ 6	$ 22,121	$ 8,748	$ (4,920)	$ (4,823)