CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Common shares [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury shares [Member]	AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Retained earnings [Member]
Beginning balance (in shares) at Dec. 31, 2018		136,330,747
Beginning balance at Dec. 31, 2018	$ 5,588	$ 3	$ 8,260	$ 12,909	$ (15,293)	$ (291)
Beginning balance (Premium Amortization on Purchased Callable Debt Securities Guidance [Member]) at Dec. 31, 2018							$ (5)	$ (5)
Comprehensive income (loss) [Abstract]
Net income	1,430			1,430
Other comprehensive income (loss), net of tax	628					628
Total comprehensive income	2,058
Dividends to shareholders	(390)			(390)
Repurchase of common shares (in shares)		(10,597,948)
Repurchase of common shares	(1,442)				(1,442)
Share-based compensation plans (in shares)		1,672,297
Share-based compensation plans	$ 188		132		56
Ending balance (in shares) at Sep. 30, 2019	127,405,096	127,405,096
Ending balance at Sep. 30, 2019	$ 5,997	$ 3	8,392	13,944	(16,679)	337
Beginning balance (in shares) at Jun. 30, 2019		131,292,759
Beginning balance at Jun. 30, 2019	6,030	$ 3	8,337	13,530	(16,109)	269
Comprehensive income (loss) [Abstract]
Net income	543			543
Other comprehensive income (loss), net of tax	68					68
Total comprehensive income	611
Dividends to shareholders	(129)			(129)
Repurchase of common shares (in shares)		(4,145,672)
Repurchase of common shares	(570)				(570)
Share-based compensation plans (in shares)		258,009
Share-based compensation plans	$ 55		55
Ending balance (in shares) at Sep. 30, 2019	127,405,096	127,405,096
Ending balance at Sep. 30, 2019	$ 5,997	$ 3	8,392	13,944	(16,679)	337
Beginning balance (in shares) at Dec. 31, 2019		123,939,234
Beginning balance at Dec. 31, 2019	5,729	$ 3	8,461	14,279	(17,276)	262
Beginning balance (Current expected credit losses guidance [Member]) at Dec. 31, 2019							$ (9)	$ (9)
Comprehensive income (loss) [Abstract]
Net income	1,357			1,357
Other comprehensive income (loss), net of tax	254					254
Total comprehensive income	1,611
Dividends to shareholders	(386)			(386)
Repurchase of common shares (in shares)		(7,392,430)
Repurchase of common shares	(1,135)				(1,135)
Share-based compensation plans (in shares)		2,084,805
Share-based compensation plans	257		216		41
Ending balance (in shares) at Sep. 30, 2020		118,631,609
Ending balance at Sep. 30, 2020	6,067	$ 3	8,677	15,241	(18,370)	516
Beginning balance (in shares) at Jun. 30, 2020		120,607,501
Beginning balance at Jun. 30, 2020	6,500	$ 3	8,622	15,510	(18,029)	394
Comprehensive income (loss) [Abstract]
Net income	(140)			(140)
Other comprehensive income (loss), net of tax	122					122
Total comprehensive income	(18)
Dividends to shareholders	(129)			(129)
Repurchase of common shares (in shares)		(2,215,753)
Repurchase of common shares	(341)				(341)
Share-based compensation plans (in shares)		239,861
Share-based compensation plans	55		55
Ending balance (in shares) at Sep. 30, 2020		118,631,609
Ending balance at Sep. 30, 2020	$ 6,067	$ 3	$ 8,677	$ 15,241	$ (18,370)	$ 516