Available-for-Sale and Held-to-Maturity Securities (Details - Maturity) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
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	41
Available-for-sale securities, due within five to ten years, amortized cost	2,408
Available-for-sale securities, due after ten years, amortized cost	10,232
Available-for-sale securities, amortized cost	12,681
Available-for-sale securities, due within one year, fair value	0
Available-for-sale securities, due within one to five years, fair value	41
Available-for-sale securities, due within five to ten years, fair value	2,362
Available-for-sale securities, due after ten years, fair value	10,154
Available-for-sale securities, fair value	12,557
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	1,166
Held-to-maturity securities, due within five to ten years, amortized cost	3,611
Held-to-maturity securities, due after ten years, amortized cost	8,193
Held-to-maturity securities, amortized cost	13,013	$ 12,248
Held-to-maturity securities, due within one year, fair value	43
Held-to-maturity securities, due within one to five years, fair value	1,203
Held-to-maturity securities, due within five to ten years, fair value	3,643
Held-to-maturity securities, due after ten years, fair value	8,234
Held-to-maturity securities, fair value	13,123	12,476
Available-for-Sale Securities Pledged As Collateral (Textuals) [Abstract]
Available-for-sale securities pledged to creditors with the right to sell or repledge	17	1,600
Held-to-Maturity Securities Pledged As Collateral (Textuals) [Abstract]
Held-to-maturity securities pledged to creditors with the right to sell or repledge	$ 700	$ 3,100