Representation and Warranty Reserve (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 |
|
| Representation and Warranty Reserve [Roll Forward] | ||||||||||||||||||
| Balance, beginning of period, | $ 40 | $ 48 | $ 53 | $ 53 | $ 54 | $ 193 | $ 40 | $ 53 | $ 53 | $ 54 | $ 193 | |||||||
| Provision, charged to gain on sale for current loan sales | 1 | 2 | 3 | 4 | 7 | 7 | 18 | |||||||||||
| Provision, charged to representation and warranty (benefit) provision | (4) | $ (6) | $ (6) | (5) | (2) | $ (6) | $ 13 | $ 5 | $ (2) | $ (15) | $ 5 | $ 29 | $ 17 | (6) | (7) | (19) | 10 | 36 |
| Total | (3) | (3) | (3) | (3) | (12) | 17 | 54 | |||||||||||
| Charge-offs, net | (1) | (2) | (1) | 2 | (1) | (18) | (193) | |||||||||||
| Balance, end of period | $ 36 | $ 40 | $ 48 | $ 53 | $ 53 | $ 54 | $ 36 | $ 48 | $ 40 | $ 53 | $ 54 | |||||||