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Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Amount

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Effective Income Tax Rate Reconciliation, Taxes on Reinsurance, Amount

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Line items represent pretax income taxes and revenue financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Income Taxes - Effective Tax Rate Reconciliation and Pretax Income (Loss) and Revenue by Tax Jurisdiction (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pre-tax Income Taxes and Revenue [Line Items]
Expected tax provision (benefit) at statutory rates in taxable jurisdictions									$ 97	$ 300	$ 316
Tax-exempt interest									(23)	(49)	(49)
Bargain purchase gain									0	(20)	(125)
Change in liability for uncertain tax positions									(15)	(26)	11
Effect of provision to tax return filing adjustments									(1)	(8)	(15)
State taxes									6	9	3
Taxes on reinsurance									6	(4)	(4)
Effects of transitional adjustments related to the Tax Act									(4)	61	0
Other									(7)	(2)	(1)
Total provision (benefit) for income taxes	$ 13	$ 14	$ 12	$ 20	$ 104	$ 105	$ (3)	$ 55	$ 59	$ 261	$ 136
Effective tax rate (as a percent)									10.20%	26.30%	13.40%
Income (loss) before provision for income taxes	$ 101	$ 175	$ 87	$ 217	$ 156	$ 313	$ 150	$ 372	$ 580	$ 991	$ 1,017
Revenue									1,002	1,739	1,677
United States [Member]
Pre-tax Income Taxes and Revenue [Line Items]
Income (loss) before provision for income taxes									461	873	921
Revenue									802	1,543	1,442
Bermuda [Member]
Pre-tax Income Taxes and Revenue [Line Items]
Income (loss) before provision for income taxes									121	145	126
Revenue									177	216	239
United Kingdom and Other [Member]
Pre-tax Income Taxes and Revenue [Line Items]
Income (loss) before provision for income taxes									(2)	(27)	(30)
Revenue									$ 23	$ (20)	$ (4)