Investments (Amortized Cost and Fair Value of Fixed Maturity Holdings by Industry Type) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Corporate Secturities by Investment Sector And Credit Rating [Line Items]
Available for Sale at Fair value - Amortized cost	$ 55,873	$ 49,548
Available-for-sale at fair value (amortized cost of $55,873 and $49,548; allowance for credit losses of $31 and $20)	60,749	56,735
Corporate Debt Securities [Member]
Corporate Secturities by Investment Sector And Credit Rating [Line Items]
Available for Sale at Fair value - Amortized cost	35,239	31,963
Available-for-sale at fair value (amortized cost of $55,873 and $49,548; allowance for credit losses of $31 and $20)	$ 38,103	$ 36,208
Percentage Of Total Available For Sales Securities	100.00%	100.00%
Financial Services Sector [Member] | Corporate Debt Securities [Member]
Corporate Secturities by Investment Sector And Credit Rating [Line Items]
Available for Sale at Fair value - Amortized cost	$ 13,101	$ 11,785
Available-for-sale at fair value (amortized cost of $55,873 and $49,548; allowance for credit losses of $31 and $20)	$ 14,045	$ 13,236
Percentage Of Total Available For Sales Securities	36.90%	36.60%
Commercial and Industrial Sector [Member] | Corporate Debt Securities [Member]
Corporate Secturities by Investment Sector And Credit Rating [Line Items]
Available for Sale at Fair value - Amortized cost	$ 17,857	$ 16,274
Available-for-sale at fair value (amortized cost of $55,873 and $49,548; allowance for credit losses of $31 and $20)	$ 19,375	$ 18,435
Percentage Of Total Available For Sales Securities	50.80%	50.90%
Utility Industry [Member] | Corporate Debt Securities [Member]
Corporate Secturities by Investment Sector And Credit Rating [Line Items]
Available for Sale at Fair value - Amortized cost	$ 4,281	$ 3,904
Available-for-sale at fair value (amortized cost of $55,873 and $49,548; allowance for credit losses of $31 and $20)	$ 4,683	$ 4,537
Percentage Of Total Available For Sales Securities	12.30%	12.50%