Mortgage Servicing Rights (Schedule of Sensitivity Analysis of Fair Value) (Details) - Mortgage servicing rights
$ in Millions |
9 Months Ended |
12 Months Ended |
|
Sep. 30, 2016
USD ($)
$ / loan
|
Dec. 31, 2015
USD ($)
$ / loan
|
| Servicing Assets at Fair Value [Line Items] |
|
|
| Option adjusted spread, Actual (as a percent) |
9.20%
|
8.24%
|
| Option adjusted spread, Decline in fair value due to 10% adverse change |
$ 295
|
$ 287
|
| Option adjusted spread, Decline in fair value due to 20% adverse change |
$ 288
|
$ 279
|
| Constant prepayment rate, Actual (as a percent) |
15.68%
|
12.63%
|
| Constant prepayment rate, Decline in fair value due to 10% adverse change |
$ 290
|
$ 285
|
| Constant prepayment rate, Decline in fair value due to 20% adverse change |
$ 280
|
$ 275
|
| Weighted average cost to service per loan, Actual (in usd per loan) | $ / loan |
70.75
|
71.86
|
| Weighted average cost to service per loan, Decline in fair value due to 10% adverse change |
$ 299
|
$ 292
|
| Weighted average cost to service per loan, Decline in fair value due to 20% adverse change |
$ 295
|
$ 288
|