Available-for-Sale and Held-to-Maturity Securities (Details - Maturity) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Available-for-Sale Securities, Debt Maturities [Abstract]
Available-for-sale securities, due within one year, amortized cost	$ 0
Available-for-sale securities, due within one to five years, amortized cost	21
Available-for-sale securities, due within five to ten years, amortized cost	2,952
Available-for-sale securities, due after ten years, amortized cost	10,910
Available-for-sale securities, amortized cost	13,883
Available-for-sale securities, due within one year, fair value	0
Available-for-sale securities, due within one to five years, fair value	21
Available-for-sale securities, due within five to ten years, fair value	2,998
Available-for-sale securities, due after ten years, fair value	10,953
Available-for-sale securities, fair value	13,972
Held-to-Maturity Securities, Debt Maturities [Abstract]
Held-to-maturity securities, due within one year, amortized cost	43
Held-to-maturity securities, due within one to five years, amortized cost	1,294
Held-to-maturity securities, due within five to ten years, amortized cost	4,234
Held-to-maturity securities, due after ten years, amortized cost	9,397
Held-to-maturity securities, amortized cost	14,968	$ 13,013
Held-to-maturity securities, due within one year, fair value	43
Held-to-maturity securities, due within one to five years, fair value	1,353
Held-to-maturity securities, due within five to ten years, fair value	4,381
Held-to-maturity securities, due after ten years, fair value	9,594
Held-to-maturity securities, fair value	15,371	13,123
Available-for-Sale Securities Pledged As Collateral (Textuals) [Abstract]
Available-for-sale debt securities pledged as collateral	17	17
Held-to-Maturity Securities Pledged As Collateral (Textuals) [Abstract]
Held-to-maturity debt securities pledged as collateral	$ 700	$ 700