Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 16
Credit Default Swaps Referencing Indices, Sell Protection
Credit Derivatives
Credit Derivative, Maximum Exposure, Undiscounted	1,094	$ 1,568
Credit Risk Derivatives, at Fair Value, Net	26	39
Credit Default Swaps Referencing Indices, Sell Protection | NAIC 3
Credit Derivatives
Credit Derivative, Maximum Exposure, Undiscounted	1,094	1,568
Credit Default Swap, Buying Protection
Credit Derivatives
Credit Derivative, Maximum Exposure, Undiscounted	1	6
Credit Risk Derivatives, at Fair Value, Net	$ 0	$ 0