Fair Value of Assets and Liabilities (Changes in Fair Values Recorded in Earnings for FVO Assets-Liabilities) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Commercial mortgage and other loans	[1]	$ 59,336		$ 59,336		$ 56,045
Other invested assets	[1],[2]	13,790		13,790		13,373
Commercial mortgage and other loans
Fair Value, Option, Quantitative Disclosures [Line Items]
Interest income		4	$ 5	10	$ 10
Fair value option loans in non-accrual status		0		0
Fair value option loans in more than 90 days past due and still accruing		0		0
Other invested assets
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value		0	33	0	110
Notes Issued by Consolidated VIEs
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value		1	(12)	1	2
Interest expense		9	$ 16	27	$ 60
Fair value option
Fair Value, Option, Quantitative Disclosures [Line Items]
Commercial mortgage and other loans		401		401		593
Other invested assets		0		0		1,945
Notes issued by consolidated VIEs		610		610		1,196
Fair value option, aggregate contractual principal
Fair Value, Option, Quantitative Disclosures [Line Items]
Commercial mortgage and other loans		396		396		582
Notes issued by consolidated VIEs		$ 632		$ 632		$ 1,233

[1] See Note 4 for details of balances associated with variable interest entities.

[2] Prior period amounts have been reclassified to conform to current period presentation. See “Adoption of ASU 2016-01” in Note 2 for details.