Shareholders' Equity - Changes in AOCI by Component (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jan. 01, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 6,839	$ 6,669	$ 6,784	$ 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		47	(64)	203	(195)
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		8	(2)	(4)	(7)
Income (loss) before income taxes		182	87	240	304
Tax (provision) benefit		(40)	(12)	(44)	(32)
Net current period other comprehensive income (loss)		34	(62)	202	(188)
Ending balance		6,722	6,634	6,722	6,634
Effect on OCI		4	4	4	2
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)		8	1	(4)	6
Net investment income		16		16
Fair value gains (losses) on FG VIEs		(8)	1	(10)	4
Income (loss) before income taxes		16	2	2	10
Tax (provision) benefit		(3)	0	(1)	(3)
Total amount reclassified from AOCI, net of tax		13	2	1	7
Total Accumulated Other Comprehensive Income [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	372	261	214	93	372
Amounts reclassified from AOCI to:
Ending balance		295	152	295	152
Net Unrealized Gains (Losses) on Investments with no OTTI [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	273	222	146	59	273
New accounting pronouncement or change in accounting principle, effect of change on net income						1
Other comprehensive income (loss) before reclassifications		90	(64)	255	(186)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		79	(63)	242	(191)
Ending balance		301	83	301	83
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)		11	1	14	(5)
Net investment income		2		2
Fair value gains (losses) on FG VIEs		0	0	0	0
Income (loss) before income taxes		13	1	16	(5)
Tax (provision) benefit		(2)	0	(3)	0
Total amount reclassified from AOCI, net of tax		11	1	13	(5)
Net Unrealized Gains (Losses) on Investments with OTTI [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	120	99	118	94	120
New accounting pronouncement or change in accounting principle, effect of change on net income						0
Other comprehensive income (loss) before reclassifications		(40)	6	(47)	(5)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		(48)	6	(43)	4
Ending balance		51	124	51	124
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)		(3)	0	(18)	11
Net investment income		14		14
Fair value gains (losses) on FG VIEs		0	0	0	0
Income (loss) before income taxes		11	0	(4)	11
Tax (provision) benefit		(3)	0	0	(2)
Total amount reclassified from AOCI, net of tax		8	0	(4)	9
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	(31)	(35)	(31)	0
New accounting pronouncement or change in accounting principle, effect of change on net income						(33)
Other comprehensive income (loss) before reclassifications		(2)	3	(4)	(1)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		4	4	4	2
Ending balance		(27)	(31)	(27)	(31)
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		0
Fair value gains (losses) on FG VIEs		(8)	1	(10)	4
Income (loss) before income taxes		(8)	1	(10)	4
Tax (provision) benefit		2	0	2	(1)
Total amount reclassified from AOCI, net of tax		(6)	1	(8)	3
Cumulative Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(29)	(37)	(23)	(37)	(29)
New accounting pronouncement or change in accounting principle, effect of change on net income						0
Other comprehensive income (loss) before reclassifications		(1)	(9)	(1)	(3)
Amounts reclassified from AOCI to:
Net current period other comprehensive income (loss)		(1)	(9)	(1)	(3)
Ending balance		(38)	(32)	(38)	(32)
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		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		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)