Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 18
Credit Derivatives [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	61	$ 0
Credit Risk Derivatives, at Fair Value, Net	(4)	$ 0
NAIC 6 | Credit Index Product [Member]
Credit Derivatives [Line Items]
Credit Derivative, Maximum Exposure, Undiscounted	$ 61