Available-for-Sale and Held-to-Maturity Securities (Details - OTTI) - USD ($) $ in Millions | Mar. 31, 2019 | Dec. 31, 2018 |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | $ 798 | $ 3,329 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 8,784 | 7,981 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 9,582 | 11,310 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (10) | (35) |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (190) | (279) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (200) | (314) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | 708 | 3,675 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 14,235 | 13,740 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 14,943 | 17,415 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (4) | (34) |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (206) | (389) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | (210) | (423) |
Agency mortgage-backed securities [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 695 | 2,945 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 8,635 | 7,826 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 9,330 | 10,771 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (10) | (34) |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (186) | (271) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (196) | (305) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | 708 | 2,802 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 12,049 | 11,587 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 12,757 | 14,389 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (4) | (31) |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (179) | (332) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | (183) | (363) |
Agency debentures [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 0 | 383 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 119 | 116 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 119 | 499 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (1) |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (3) | (6) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (3) | (7) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | 0 | 776 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 811 | 666 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 811 | 1,442 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (2) |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (6) | (14) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | (6) | (16) |
US Treasuries [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 102 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | |
Debt Securities, Available-for-sale, Unrealized Loss Position | 102 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 0 | |
Other agency debt securities [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 0 | 0 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 30 | 30 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 30 | 30 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (1) | (2) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (1) | (2) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | 0 | 97 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 1,375 | 1,487 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 1,375 | 1,584 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (1) |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (21) | (43) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | (21) | (44) |
Municipal bonds [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | | 0 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | | 9 |
Debt Securities, Available-for-sale, Unrealized Loss Position | | 9 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | | 0 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | | 0 |
Other [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 1 | 1 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 1 | 1 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | $ 0 | $ 0 |