Available-for-Sale and Held-to-Maturity Securities (Details - OTTI) - USD ($) $ in Millions | Sep. 30, 2019 | Dec. 31, 2018 |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | $ 1,475 | $ 3,329 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 3,118 | 7,981 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 4,593 | 11,310 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (16) | (35) |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (41) | (279) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (57) | (314) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | 403 | 3,675 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 4,344 | 13,740 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 4,747 | 17,415 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (3) | (34) |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (40) | (389) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | (43) | (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 | 843 | 2,945 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 3,118 | 7,826 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 3,961 | 10,771 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (4) | (34) |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (41) | (271) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | (45) | (305) |
Schedule of Held-to-maturity Securities [Line Items] | | |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | 403 | 2,802 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 4,166 | 11,587 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 4,569 | 14,389 |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (3) | (31) |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (39) | (332) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | (42) | (363) |
Agency debentures [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | | 383 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | | 116 |
Debt Securities, Available-for-sale, Unrealized Loss Position | | 499 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | | (1) |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | | (6) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | | (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 | 35 | 666 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 35 | 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 | 0 | (14) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | 0 | (16) |
US Treasuries [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 429 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | |
Debt Securities, Available-for-sale, Unrealized Loss Position | 429 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (11) | |
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 | (11) | |
Non-agency asset-backed securities [Member] | | |
Debt Securities, Available-for-sale [Line Items] | | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 203 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | |
Debt Securities, Available-for-sale, Unrealized Loss Position | 203 | |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (1) | |
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 | (1) | |
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 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | | 30 |
Debt Securities, Available-for-sale, Unrealized Loss Position | | 30 |
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 | | (2) |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | | (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 | 143 | 1,487 |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value | 143 | 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 | (1) | (43) |
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss | $ (1) | (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 |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position | | 1 |
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 |