Derivative Instruments and Hedging Activities (Details - Fair Value Hedge) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Total interest income	$ 2,111	$ 2,009	$ 1,571
Changes in fair value of hedged item			(51)
Changes in fair value of derivatives			37
Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total interest income	2,111	2,009
Net gain (loss) on fair value hedging relationships	26	(13)
Agency debentures [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of hedged item			(3)
Changes in fair value of derivatives			1
Agency debentures [Member] | Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amounts recognized as interest settlements on derivatives	1	(3)
Changes in fair value of hedged item	2	(69)
Changes in fair value of derivatives	(4)	68
Net gain (loss) on fair value hedging relationships	(1)	(4)
Agency mortgage-backed securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of hedged item			(48)
Changes in fair value of derivatives			$ 36
Agency mortgage-backed securities [Member] | Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amounts recognized as interest settlements on derivatives	(7)	(15)
Amortization of basis adjustment	35	24
Changes in fair value of hedged item	722	(111)
Changes in fair value of derivatives	(723)	93
Net gain (loss) on fair value hedging relationships	$ 27	$ (9)