Available-for-Sale Securities (Details - OTTI) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	$ 8,993	$ 10,186
Available-for-sale securities, twelve months or longer, fair value	1,813	1,620
Available-for-sale securities, fair value	10,806	11,806
Available-for-sale securities, less than twelve months, aggregate losses	(196)	(346)
Available-for-sale securities, twelve months or longer, aggregate losses	(49)	(57)
Available-for-sale securities, aggregate losses	(245)	(403)
Agency Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	8,277	9,281
Available-for-sale securities, twelve months or longer, fair value	1,813	1,620
Available-for-sale securities, fair value	10,090	10,901
Available-for-sale securities, less than twelve months, aggregate losses	(173)	(279)
Available-for-sale securities, twelve months or longer, aggregate losses	(49)	(57)
Available-for-sale securities, aggregate losses	(222)	(336)
Agency Debentures [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	374	454
Available-for-sale securities, twelve months or longer, fair value	0	0
Available-for-sale securities, fair value	374	454
Available-for-sale securities, less than twelve months, aggregate losses	(14)	(21)
Available-for-sale securities, twelve months or longer, aggregate losses	0	0
Available-for-sale securities, aggregate losses	(14)	(21)
U.S. Treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	290	407
Available-for-sale securities, twelve months or longer, fair value	0
Available-for-sale securities, fair value	290	407
Available-for-sale securities, less than twelve months, aggregate losses	(8)	(45)
Available-for-sale securities, twelve months or longer, aggregate losses	0
Available-for-sale securities, aggregate losses	(8)	(45)
Agency Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	33	24
Available-for-sale securities, twelve months or longer, fair value	0	0
Available-for-sale securities, fair value	33	24
Available-for-sale securities, less than twelve months, aggregate losses	(1)	(1)
Available-for-sale securities, twelve months or longer, aggregate losses	0	0
Available-for-sale securities, aggregate losses	(1)	(1)
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	12	13
Available-for-sale securities, twelve months or longer, fair value	0	0
Available-for-sale securities, fair value	12	13
Available-for-sale securities, less than twelve months, aggregate losses	0	0
Available-for-sale securities, twelve months or longer, aggregate losses	0	0
Available-for-sale securities, aggregate losses	0	0
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, less than twelve months, fair value	7	7
Available-for-sale securities, twelve months or longer, fair value	0
Available-for-sale securities, fair value	7	7
Available-for-sale securities, less than twelve months, aggregate losses	0	0
Available-for-sale securities, twelve months or longer, aggregate losses	0
Available-for-sale securities, aggregate losses	$ 0	$ 0

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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