Accounting for Derivative Instruments and Hedging Activities (Details - Fair Value Hedge) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge, Hedging Instrument	$ (7)	$ (133)	$ 107
Fair Value Hedge, Hedged Item	6	123	(107)
Fair Value Hedge, Hedge Ineffectiveness	(1)	(10)	0
Derivatives Textuals [Abstract]
Collateral Already Posted, Aggregate Fair Value	130
Derivative, Net Liability Position, Aggregate Fair Value	45
Excess Collateral Derivatives In Net Liability Position	85
Agency Debentures [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge, Hedging Instrument	(3)	(100)	73
Fair Value Hedge, Hedged Item	3	91	(72)
Fair Value Hedge, Hedge Ineffectiveness	0	(9)	1
Agency mortgage-backed securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge, Hedging Instrument	(4)	(33)	34
Fair Value Hedge, Hedged Item	3	32	(35)
Fair Value Hedge, Hedge Ineffectiveness	$ (1)	$ (1)	$ (1)