AOCI Rollforward (Details 2) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ 269	$ (179)	$ (291)	$ 229
Cumulative effect of change in accounting policies						$ 5	$ 0
OCI before reclassifications		60	(62)	625	(461)
Amounts reclassified from AOCI		8	(3)	3	(11)
Total other comprehensive income (loss), net of tax		68	(65)	628	(472)
Ending balance		337	(244)	337	(244)
Accumulated Other Comprehensive Income (Loss) Available For Sale Securities Impairment Other than Credit		(1)	(1)	(1)	(1)
Net unrealized gains (losses) on securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		590	93	20	486
OCI before reclassifications		82	(59)	656	(443)
Amounts reclassified from AOCI		8	(3)	4	(11)
Total other comprehensive income (loss), net of tax		90	(62)	660	(454)
Ending balance	[1]	680	31	680	31
Net unrealized gains (losses) on derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		7	8	8	8
OCI before reclassifications		0	0	0	0
Amounts reclassified from AOCI		0	0	(1)	0
Total other comprehensive income (loss), net of tax		0	0	(1)	0
Ending balance		7	8	7	8
Defined benefit plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(120)	(97)	(120)	(97)
OCI before reclassifications		0	0	0	0
Amounts reclassified from AOCI		0	0	0	0
Total other comprehensive income (loss), net of tax		0	0	0	0
Ending balance		(120)	(97)	(120)	(97)
Foreign currency translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(207)	(182)	(198)	(167)
OCI before reclassifications		(22)	(3)	(31)	(18)
Amounts reclassified from AOCI		0	0	0	0
Total other comprehensive income (loss), net of tax		(22)	(3)	(31)	(18)
Ending balance		(229)	(185)	(229)	(185)
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1)	(1)	(1)	(1)
OCI before reclassifications		0	0	0	0
Amounts reclassified from AOCI		0	0	0	0
Total other comprehensive income (loss), net of tax		0	0	0	0
Ending balance		$ (1)	$ (1)	$ (1)	$ (1)
Cumulative effect of adoption of equity securities guidance
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of change in accounting policies							1
Cumulative effect of adoption of equity securities guidance | Net unrealized gains (losses) on securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of change in accounting policies							$ 1

[1] Includes $1 million of noncredit related impairments on securities and net unrealized gains (losses) on previously impaired securities as of both September 30, 2019 and September 30, 2018.