Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Credit Derivatives [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 45
Cash flow hedge, reclassified to earnings, net	0	$ 0
Exposure Associated With Collateralization Events	0	0
Maximum [Member]
Credit Derivatives [Line Items]
Non-performance Risk Adjustment	$ 0
Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Exposure		$ 0