Available-for-Sale and Held-to-Maturity Securities (Details - OTTI) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017 |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 7,519 | $ 4,654 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 8,808 | 8,492 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 16,327 | 13,146 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (120) | (23) |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (366) | (241) |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (486) | (264) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 12,387 | 10,952 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 5,193 | 6,260 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 17,580 | 17,212 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (260) | (83) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (202) | (147) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss | (462) | (230) |
Agency mortgage-backed securities [Member] | | |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 7,269 | 4,638 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 8,661 | 8,027 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 15,930 | 12,665 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (118) | (23) |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (358) | (224) |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (476) | (247) |
Agency Debentures [Member] | | |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 202 | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 115 | 283 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 317 | 283 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (2) | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (7) | (12) |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (9) | (12) |
US Treasury Securities [Member] | | |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | | 147 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | | 147 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | | (4) |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | | (4) |
Agency Debt Securities [Member] | | |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 48 | 9 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 22 | 24 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 70 | 33 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (1) | (1) |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (1) | (1) |
Municipal Bonds [Member] | | |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 10 | 11 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | 10 | 11 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | 0 | 0 |
Equity Securities [Member] | | |
Schedule of Available-for-sale Securities [Line Items] | | |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | | 7 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | | 7 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | | 0 |
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | | 0 |
Agency mortgage-backed securities [Member] | | |
Schedule of Held-to-maturity Securities [Line Items] | | |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 10,988 | 9,982 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 3,836 | 4,906 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 14,824 | 14,888 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (234) | (78) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (152) | (115) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss | (386) | (193) |
Agency Debentures [Member] | | |
Schedule of Held-to-maturity Securities [Line Items] | | |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 817 | 597 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 151 | 9 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 968 | 606 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (16) | (2) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (3) | 0 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss | (19) | (2) |
Agency Debt Securities [Member] | | |
Schedule of Held-to-maturity Securities [Line Items] | | |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 582 | 373 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 1,206 | 1,345 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 1,788 | 1,718 |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (10) | (3) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (47) | (32) |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ (57) | $ (35) |