Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 687	$ 476	$ 241	$ (319)	$ 378	$ 381	$ 582	$ 374	$ 1,085	$ 1,715	$ 1,263
Other Comprehensive Income (Loss), Net of Tax									508	654	(289)
Translation adjustments and net investment hedges, net change									0	1	(2)
Comprehensive Income									1,593	2,369	974
Investment Securities
Net unrealized gains (losses) arising during the period									564	741	(287)
Net realized gains reclassified to net income									132	60	8
Other Comprehensive Income (Loss), Net of Tax									432	681	(295)
Translation Adjustments
Other Comprehensive Income (Loss), Net of Tax									3	5	(11)
Net Investment Hedges
Other Comprehensive Income (Loss), Net of Tax									(3)	(4)	9
Cash Flow Hedges
Net unrealized gains (losses) arising during the period									129	(7)	10
Net realized gains reclassified to net income									49	10	2
Other Comprehensive Income (Loss), Net of Tax									80	(17)	8
Defined benefit pension plans
Other Comprehensive Income (Loss), Net of Tax									$ (4)	$ (11)	$ 0