Loans Held-for-Sale (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | 12 Months Ended | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Jun. 30, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Jun. 30, 2014 |
Mar. 31, 2014 |
Dec. 31, 2013 |
Sep. 30, 2013 |
Jun. 30, 2013 |
Mar. 31, 2013 |
Jun. 30, 2016 |
Jun. 30, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||||||||||||||
| Loans held-for-sale | $ 3,091 | $ 2,576 | $ 1,244 | $ 3,091 | $ 2,576 | $ 1,244 | ||||||||||||
| Net gain on loan sales | 90 | 46 | $ 68 | $ 83 | $ 91 | 53 | $ 52 | $ 55 | $ 45 | $ 45 | $ 75 | $ 144 | $ 137 | 165 | $ 174 | 288 | 206 | $ 402 |
| Loans held-for-sale recorded at lower of cost or fair value | 20 | 35 | 48 | 20 | 35 | 48 | ||||||||||||
| Gain (Loss) on Sales of Loans, Net | 90 | 46 | $ 68 | 83 | $ 91 | 53 | $ 52 | $ 55 | $ 45 | $ 45 | $ 75 | $ 144 | $ 137 | 165 | 174 | 288 | 206 | $ 402 |
| Loans held-for-sale | ||||||||||||||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||||||||||||||
| Net gain on loan sales | 85 | 83 | 151 | 174 | ||||||||||||||
| Gain (Loss) on Sales of Loans, Net | 85 | $ 83 | 151 | $ 174 | ||||||||||||||
| Consumer Loan | Residential first mortgage loans | ||||||||||||||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||||||||||||||
| Loans held-for-sale | $ 3,100 | $ 2,600 | $ 1,200 | $ 3,100 | $ 2,600 | $ 1,200 | ||||||||||||