Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other investment related gains (losses), net										$ 122	$ (142)	$ 211
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Portion in Other Comprehensive Loss, before Tax, Including Portion Attributable to Noncontrolling Interest										0	0	0
Investment income, net of related expenses										2,520	2,139	2,155
Deferred Policy Acquisition Cost, Amortization Expense, Unrealized Investment Gains (Losses)										97	(27)	8
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax										1	1	(12)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax										23	(1)	11
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		$ 308	$ 347	$ 260	$ 217	$ 138	$ 323	$ 247	$ 138	1,132	846	1,143
Income Tax Expense (Benefit)										(262)	(130)	679
Net Income (Loss) Attributable to Parent		$ 235	$ 263	$ 202	$ 170	$ 110	$ 301	$ 205	$ 100	870	716	$ 1,822
Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	[1]									1	(1)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	[1]									(5)	(6)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest										(4)	(5)
Income Tax Expense (Benefit)										1	1
Net Income (Loss) Attributable to Parent										(3)	(4)
Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other investment related gains (losses), net										84	(122)
Deferred Policy Acquisition Cost, Amortization Expense, Unrealized Investment Gains (Losses)	[2]									97	(27)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest										182	(149)
Income Tax Expense (Benefit)										(38)	31
Net Income (Loss) Attributable to Parent										144	(118)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income (Loss) Attributable to Parent										141	(122)
Interest Rate Options [Member] | Unrealized Gains Losses On Available For Sale Securities [Member] | Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]									1	0
Currency Swap [Member] | Unrealized Gains Losses On Available For Sale Securities [Member] | Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]									0	0
Forward Contracts [Member] | Unrealized Gains Losses On Available For Sale Securities [Member] | Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]									$ 0	$ 0

[1] See Note 10 for information on employee benefit plans.

[2] See Note 8 for information on deferred policy acquisition costs.

[3] See Note 5 for information on cash flow hedges.