Derivative Instruments And Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Forward Contract Indexed to Issuer's Equity [Line Items]
Derivative, Notional Amount	$ 53,036	$ 59,116
Cash Collateral Placed with Counterparties Excluding Cash Collateral Associated with Repurchase Agreements	104	103
Securities Collateral Placed with Counterparties	78	86
Non-derivative Cash Collateral Placed with Counterparties Associated with the Repurchase Agreements	2	21
Cash Collateral Received from Counterparties, Excluding Collateral Associated with Repurchase Agreements	125	82
Non-derivative Cash Collateral Received from Counterparties Associated with the Repurchase Agreements.	1
Non-cash collateral received	3	7
Designated as Hedging Instrument [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Derivative, Notional Amount	10,920	14,340
Designated as Hedging Instrument [Member] | Equity Contract [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Derivative, Notional Amount	25	32
Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Equity Contract [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Derivative, Notional Amount	$ 25	$ 32