Income Tax (Impact of U.S. Tax Reform) (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal corporate income tax rate	21.00%				35.00%
Transition tax rate	6.20%
Provision for income tax expense (benefit)		$ 1,509	$ 886	$ 1,179
Deferred Federal Income Tax Expense (Benefit)		(115)	(235)	342
Deferred Tax Liabilities, Investments		4,421	4,170
Other Assets
Transition tax rate	8.00%
Cash and Cash Equivalents
Transition tax rate	15.50%
Impact of U.S. Tax Reform
Other Adjustments, Amount		0	(326)	78
Provision for income tax expense (benefit)			(326)	66
Deferred Federal Income Tax Expense (Benefit)			(9)	(402)
Alternative Minimum Tax Credits
Deferred Federal Income Tax Expense (Benefit)			(9)	0
Foreign Tax Authority | Impact of U.S. Tax Reform
Repatriation of Foreign Earnings			317	468
Deferred Tax Liabilities, Investments		281
GILTI [Member] | Impact of U.S. Tax Reform
Effective Income Tax Rate Reconciliation, Tax Contingency, Foreign, Amount		43	12
Provision for income tax expense (benefit)			35	45
Other limited partnership interests
Gross Investment Income, Operating		$ 1,000	$ 825	731
Other limited partnership interests | Impact of U.S. Tax Reform
Provision for income tax expense (benefit)				(125)
Gross Investment Income, Operating				$ 46