Available-for-Sale and Held-to-Maturity Securities (Details - Maturity) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Available-for-Sale Securities, Debt Maturities [Abstract]
Available-for-sale securities, due within one year, amortized cost	$ 87
Available-for-sale securities, due within one to five years, amortized cost	360
Available-for-sale securities, due within five to ten years, amortized cost	9,379
Available-for-sale securities, due after ten years, amortized cost	8,882
Available-for-sale debt securities, amortized cost basis	18,708	$ 23,126
Available-for-sale securities, due within one year, fair value	87
Available-for-sale securities, due within one to five years, fair value	364
Available-for-sale securities, due within five to ten years, fair value	10,107
Available-for-sale securities, due after ten years, fair value	8,943
Available-for-sale securities, fair value	19,501	23,153
Held-to-Maturity Securities, Debt Maturities [Abstract]
Held-to-maturity securities, due within one year, amortized cost	47
Held-to-maturity securities, due within one to five years, amortized cost	2,000
Held-to-maturity securities, due within five to ten years, amortized cost	3,035
Held-to-maturity securities, due after ten years, amortized cost	16,887
Held-to-maturity securities, amortized cost	21,969	21,884
Held-to-maturity securities, due within one year, fair value	47
Held-to-maturity securities, due within one to five years, fair value	2,029
Held-to-maturity securities, due within five to ten years, fair value	3,102
Held-to-maturity securities, due after ten years, fair value	17,068
Held-to-maturity securities, fair value	22,246	21,491
Collateral Pledged [Member]
Financing Receivable, Impaired [Line Items]
Held-to-maturity debt securities pledged as collateral	7,400	6,300
Available-for-sale debt securities pledged as collateral	$ 456	$ 151