Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions | Sep. 30, 2016 | Jun. 30, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Dec. 31, 2014 |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | $ 1,115 | | $ 1,294 | | | |
Loans held-for-sale | 3,352 | | 2,541 | | | |
Loans held-for-investment | 80 | | 111 | | | |
Mortgage servicing rights | 302 | | 296 | | | |
Total assets at fair value | 3,432 | | 2,652 | | | |
Agency - Commercial | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 510 | | 766 | | | |
Agency - Residential | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 573 | | 514 | | | |
Municipal obligations | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 32 | | 14 | | | |
Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 1,115 | | 1,294 | | | |
Loans held-for-sale | 3,394 | | 2,578 | | | |
Loans held-for-investment | 6,134 | | 6,121 | | | |
Mortgage servicing rights | 302 | | 296 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | 60 | | 84 | | | |
Warrant liabilities | (10) | | (8) | | | |
Long-term Debt, Fair Value | 257 | | 89 | | | |
Level 1 | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Loans held-for-sale | 0 | | 0 | | | |
Loans held-for-investment | 0 | | 0 | | | |
Mortgage servicing rights | 0 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | 0 | | 0 | | | |
Warrant liabilities | 0 | | 0 | | | |
Long-term Debt, Fair Value | 0 | | 0 | | | |
Level 2 | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 1,115 | | 1,294 | | | |
Loans held-for-sale | 3,394 | | 2,578 | | | |
Loans held-for-investment | 8 | | 6 | | | |
Mortgage servicing rights | 0 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | 0 | | 0 | | | |
Warrant liabilities | (10) | | (8) | | | |
Long-term Debt, Fair Value | 257 | | 89 | | | |
Level 3 | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Loans held-for-sale | 0 | | 0 | | | |
Loans held-for-investment | 6,126 | | 6,115 | | | |
Mortgage servicing rights | 302 | | 296 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | 60 | | 84 | | | |
Warrant liabilities | 0 | | 0 | | | |
Long-term Debt, Fair Value | 0 | | 0 | | | |
Recurring | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Mortgage servicing rights | 302 | | 296 | | | |
Total derivative assets | 119 | | 58 | | | |
Total assets at fair value | 4,968 | | 4,301 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (93) | | (18) | | | |
Warrant liabilities | (10) | | (8) | | | |
DOJ litigation settlement | (60) | | (84) | | | |
Total liabilities at fair value | (163) | | (110) | | | |
Recurring | Total Fair Value | Residential first mortgage loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-sale | 3,352 | | 2,541 | | | |
Loans held-for-investment | 8 | | 6 | | | |
Recurring | Total Fair Value | Second mortgage | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 41 | | 42 | | | |
Recurring | Total Fair Value | Agency - Commercial | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 510 | | 766 | | | |
Recurring | Total Fair Value | Agency - Residential | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 573 | | 514 | | | |
Recurring | Total Fair Value | Municipal obligations | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 32 | | 14 | | | |
Recurring | Total Fair Value | HELOC loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 31 | | 64 | | | |
Recurring | Level 1 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Mortgage servicing rights | 0 | | 0 | | | |
Total derivative assets | 1 | | 0 | | | |
Total assets at fair value | 1 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | (1) | | | |
Warrant liabilities | 0 | | 0 | | | |
DOJ litigation settlement | 0 | | 0 | | | |
Total liabilities at fair value | 0 | | (1) | | | |
Recurring | Level 1 | Residential first mortgage loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-sale | 0 | | 0 | | | |
Loans held-for-investment | 0 | | 0 | | | |
Recurring | Level 1 | Second mortgage | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 0 | | 0 | | | |
Recurring | Level 1 | Agency - Commercial | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Recurring | Level 1 | Agency - Residential | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Recurring | Level 1 | Municipal obligations | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Recurring | Level 1 | HELOC loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 0 | | 0 | | | |
Recurring | Level 2 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Mortgage servicing rights | 0 | | 0 | | | |
Total derivative assets | 55 | | 32 | | | |
Total assets at fair value | 4,530 | | 3,873 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (93) | | (17) | | | |
Warrant liabilities | (10) | | (8) | | | |
DOJ litigation settlement | 0 | | 0 | | | |
Total liabilities at fair value | (103) | | (25) | | | |
Recurring | Level 2 | Residential first mortgage loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-sale | 3,352 | | 2,541 | | | |
Loans held-for-investment | 8 | | 6 | | | |
Recurring | Level 2 | Second mortgage | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 0 | | 0 | | | |
Recurring | Level 2 | Agency - Commercial | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 510 | | 766 | | | |
Recurring | Level 2 | Agency - Residential | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 573 | | 514 | | | |
Recurring | Level 2 | Municipal obligations | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 32 | | 14 | | | |
Recurring | Level 2 | HELOC loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 0 | | 0 | | | |
Recurring | Level 3 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 374 | $ 383 | 402 | $ 519 | $ 558 | $ 545 |
Mortgage servicing rights | 302 | | 296 | | | |
Total derivative assets | 63 | | 26 | | | |
Total assets at fair value | 437 | | 428 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | 0 | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | | | | $ 116 | $ 120 | $ 166 |
Warrant liabilities | 0 | | 0 | | | |
DOJ litigation settlement | (60) | | (84) | | | |
Total liabilities at fair value | (60) | | (84) | | | |
Recurring | Level 3 | Residential first mortgage loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-sale | 0 | | 0 | | | |
Loans held-for-investment | 0 | | 0 | | | |
Recurring | Level 3 | Second mortgage | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | 41 | | 42 | | | |
Recurring | Level 3 | Agency - Commercial | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Recurring | Level 3 | Agency - Residential | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Recurring | Level 3 | Municipal obligations | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Investment securities available-for-sale | 0 | | 0 | | | |
Recurring | Level 3 | HELOC loans | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Loans held-for-investment | | | 64 | | | |
Rate lock commitments | Recurring | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 63 | | 26 | | | |
Rate lock commitments | Recurring | Level 1 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | 0 | | | |
Rate lock commitments | Recurring | Level 2 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | 0 | | | |
Rate lock commitments | Recurring | Level 3 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 63 | | 26 | | | |
Mortgage-backed Securities, US Government Agencies [Member] | Recurring | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 2 | | 7 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (24) | | (6) | | | |
Mortgage-backed Securities, US Government Agencies [Member] | Recurring | Level 1 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | 0 | | | |
Mortgage-backed Securities, US Government Agencies [Member] | Recurring | Level 2 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 2 | | 7 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (24) | | (6) | | | |
Mortgage-backed Securities, US Government Agencies [Member] | Recurring | Level 3 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | 0 | | | |
Interest rate swaps and swaptions | Recurring | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 53 | | 25 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (17) | | | | | |
Interest rate swaps and swaptions | Recurring | Level 1 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | | | | |
Interest rate swaps and swaptions | Recurring | Level 2 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 53 | | 25 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (17) | | | | | |
Interest rate swaps and swaptions | Recurring | Level 3 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | 0 | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | | | | |
U.S. Treasury, swap and euro dollar futures | Recurring | Total Fair Value | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 1 | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | (1) | | | |
U.S. Treasury, swap and euro dollar futures | Recurring | Level 1 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 1 | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | (1) | | | |
U.S. Treasury, swap and euro dollar futures | Recurring | Level 2 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | 0 | | | |
U.S. Treasury, swap and euro dollar futures | Recurring | Level 3 | | | | | | |
Assets, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative assets | 0 | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | 0 | | | |
Interest rate swaps on FHLB advances | Recurring | Total Fair Value | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (52) | | (4) | | | |
Interest rate swaps on FHLB advances | Recurring | Level 1 | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | 0 | | 0 | | | |
Interest rate swaps on FHLB advances | Recurring | Level 2 | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | (52) | | (4) | | | |
Interest rate swaps on FHLB advances | Recurring | Level 3 | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | $ 0 | | 0 | | | |
Interest rate swaps | Recurring | Total Fair Value | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | (7) | | | |
Interest rate swaps | Recurring | Level 1 | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | 0 | | | |
Interest rate swaps | Recurring | Level 2 | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | (7) | | | |
Interest rate swaps | Recurring | Level 3 | | | | | | |
Liabilities, Fair Value Disclosure [Abstract] | | | | | | |
Total derivative liabilities | | | $ 0 | | | |