CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Common Shares [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Shares [Member]	Accumulated Other Comprehensive Income [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Accumulated Other Comprehensive Income [Member]
Balances (in shares) at Dec. 31, 2017		146,634,664
Balances at Dec. 31, 2017	$ 5,995	$ 3	$ 8,085	$ 11,326	$ (13,648)	$ 229			$ (1)
Balances (Equity securities guidance [Member]) at Dec. 31, 2017								$ 1	$ (1)
Comprehensive income (loss):
Net income	2,098			2,098
Other comprehensive income (loss), net of tax	(519)					(519)
Total comprehensive income (loss)	1,579
Dividends to shareholders	(516)			(516)
Repurchase of common shares	(1,705)				(1,705)
Repurchase of common shares (in shares)		(12,124,840)
Share-based compensation plans	235		175		60
Share-based compensation plans (in shares)		1,820,923
Balances (in shares) at Dec. 31, 2018		136,330,747
Balances at Dec. 31, 2018	5,588	$ 3	8,260	12,909	(15,293)	(291)
Balances (Premium Amortization on Purchased Callable Debt Securities Guidance [Member]) at Dec. 31, 2018							$ (5)	(5)
Comprehensive income (loss):
Net income	1,893			1,893
Other comprehensive income (loss), net of tax	553					553
Total comprehensive income (loss)	2,446
Dividends to shareholders	(518)			(518)
Repurchase of common shares	(2,039)				(2,039)
Repurchase of common shares (in shares)		(14,396,367)
Share-based compensation plans	257		201		56
Share-based compensation plans (in shares)		2,004,854
Balances (in shares) at Dec. 31, 2019		123,939,234
Balances at Dec. 31, 2019	5,729	$ 3	8,461	14,279	(17,276)	262
Balances (Current expected credit losses guidance [Member]) at Dec. 31, 2019							$ (9)	$ (9)
Comprehensive income (loss):
Net income	1,534			1,534
Other comprehensive income (loss), net of tax	367					367
Total comprehensive income (loss)	1,901
Dividends to shareholders	(512)			(512)
Repurchase of common shares	(1,647)				(1,647)
Repurchase of common shares (in shares)		(10,241,160)
Share-based compensation plans	405		361		44
Share-based compensation plans (in shares)		3,067,539
Balances (in shares) at Dec. 31, 2020		116,765,613
Balances at Dec. 31, 2020	$ 5,867	$ 3	$ 8,822	$ 15,292	$ (18,879)	$ 629