Variable Interest Entities - Narrative (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) policies Entity	Mar. 31, 2018 USD ($) Entity	Dec. 31, 2018 USD ($) policies Entity	Dec. 31, 2017 USD ($)
Variable Interest Entity [Line Items]
Effect on shareholders' equity (decrease) increase	$ 6,669,000,000	$ 6,784,000,000	$ 6,555,000,000	$ 6,839,000,000
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt	0
Fair value gains (losses) on FG VIEs (1)	5,000,000	4,000,000
Variable Interest Entity, Other Consolidated [Abstract]
Other consolidated VIE assets	88,000,000		87,000,000
Other consolidated VIE liabilities	$ 13,000,000		$ 21,000,000
Number of Policies Monitored | policies	18,000
Number of Policies Monitored, Not Within the Scope of ASC 810 | policies	16,000
Number of Policies that Contain Provisions for Consolidation | policies	110		110
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Effect on shareholders' equity (decrease) increase	$ 0		$ 1,000,000
Fair value gains (losses) on FG VIEs (1)	$ 5,000,000	$ 4,000,000
Variable Interest Entity, Other Consolidated [Abstract]
Number of Entities Consolidated | Entity	31		31
Number of Entities Deconsolidated | Entity		1
Residential Mortgage Backed Securities and Other Insurance Products [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Change in the instrument specific credit risk of the VIEs' assets	$ 6,000,000	$ 2,000,000