Shareholders' Equity - Changes in AOCI by Component (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 01, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 6,839	$ 6,722	$ 6,634	$ 6,555	$ 6,839
New accounting pronouncement or change in accounting principle, effect of change on net income						$ (32)
Other comprehensive income (loss) before reclassifications		34	(83)	237	(278)
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		16	(7)	12	(14)
Income (loss) before income taxes		86	175	326	479
Tax (provision) benefit		(17)	(14)	(61)	(46)
Net current period other comprehensive income (loss)		24	(74)	226	(262)
Ending balance		6,652	6,583	6,652	6,583
Effect on OCI		0	(3)	4	(1)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		17	(7)	13	(13)
Net investment income				16
Fair value gains (losses) on FG VIEs		(3)	(2)	(13)	(6)
Income (loss) before income taxes		14	(9)	16	(19)
Tax (provision) benefit		(4)	0	(5)	3
Total amount reclassified from AOCI, net of tax		10	(9)	11	(16)
Total Accumulated Other Comprehensive Income [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	372	295	152	93	372
Amounts reclassified from AOCI to:
Ending balance		319	78	319	78
Net Unrealized Gains (Losses) on Investments with no OTTI [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	273	301	83	59	273
New accounting pronouncement or change in accounting principle, effect of change on net income						1
Other comprehensive income (loss) before reclassifications		57	(59)	312	(245)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		33	(59)	275	(250)
Ending balance		334	24	334	24
Net Unrealized Gains (Losses) on Investments with no OTTI [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		29	1	43	6
Net investment income				2
Fair value gains (losses) on FG VIEs		0	0	0	0
Income (loss) before income taxes		29	1	45	6
Tax (provision) benefit		(5)	(1)	(8)	(1)
Total amount reclassified from AOCI, net of tax		24	0	37	5
Net Unrealized Gains (Losses) on Investments with OTTI [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	120	51	124	94	120
New accounting pronouncement or change in accounting principle, effect of change on net income						0
Other comprehensive income (loss) before reclassifications		(21)	(16)	(68)	(21)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		(9)	(9)	(52)	(5)
Ending balance		42	115	42	115
Net Unrealized Gains (Losses) on Investments with OTTI [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		(12)	(8)	(30)	(19)
Net investment income				14
Fair value gains (losses) on FG VIEs		0	0	0	0
Income (loss) before income taxes		(12)	(8)	(16)	(19)
Tax (provision) benefit		0	1	0	3
Total amount reclassified from AOCI, net of tax		(12)	(7)	(16)	(16)
Net Unrealized Gains (Losses) on FG VIE Liabilities with Recourse due to Instrument Specific Credit Risk [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	0	(27)	(31)	(31)	0
New accounting pronouncement or change in accounting principle, effect of change on net income						(33)
Other comprehensive income (loss) before reclassifications		(2)	(5)	(6)	(6)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		0	(3)	4	(1)
Ending balance		(27)	(34)	(27)	(34)
Net Unrealized Gains (Losses) on FG VIE Liabilities with Recourse due to Instrument Specific Credit Risk [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		0	0	0	0
Net investment income				0
Fair value gains (losses) on FG VIEs		(3)	(2)	(13)	(6)
Income (loss) before income taxes		(3)	(2)	(13)	(6)
Tax (provision) benefit		1	0	3	1
Total amount reclassified from AOCI, net of tax		(2)	(2)	(10)	(5)
Cumulative Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(29)	(38)	(32)	(37)	(29)
New accounting pronouncement or change in accounting principle, effect of change on net income						0
Other comprehensive income (loss) before reclassifications		0	(3)	(1)	(6)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		0	(3)	(1)	(6)
Ending balance		(38)	(35)	(38)	(35)
Cumulative Translation Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		0	0	0	0
Net investment income				0
Fair value gains (losses) on FG VIEs		0	0	0	0
Income (loss) before income taxes		0	0	0	0
Tax (provision) benefit		0	0	0	0
Total amount reclassified from AOCI, net of tax		0	0	0	0
Cash Flow Hedge [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	8	8	8	8	8
New accounting pronouncement or change in accounting principle, effect of change on net income						$ 0
Other comprehensive income (loss) before reclassifications		0	0	0	0
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		0	0	0	0
Ending balance		8	8	8	8
Cash Flow Hedge [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		0	0	0	0
Net investment income				0
Fair value gains (losses) on FG VIEs		0	0	0	0
Income (loss) before income taxes		0	0	0	0
Tax (provision) benefit		0	0	0	0
Total amount reclassified from AOCI, net of tax		$ 0	$ 0	$ 0	$ 0
Accounting Standards Update 2016-01 [Member]
Amounts reclassified from AOCI to:
Effect on OCI	32
Accounting Standards Update 2016-01 [Member] | Total Accumulated Other Comprehensive Income [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
New accounting pronouncement or change in accounting principle, effect of change on net income	$ (32)