Federal Home Loan Bank Advances (Other Disclosures) (Details) - USD ($)
$ in Millions |
3 Months Ended |
6 Months Ended |
12 Months Ended |
Jun. 30, 2016 |
Dec. 31, 2015 |
Jun. 30, 2015 |
Dec. 31, 2013 |
Jun. 30, 2016 |
Jun. 30, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Long-term Federal Home Loan Bank advances |
$ 1,577
|
$ 1,425
|
|
|
$ 1,577
|
|
$ 1,425
|
|
|
| Gain (loss) on extinguishment of debt |
|
|
|
|
|
|
0
|
$ 0
|
$ (178)
|
| FHLB advances, maximum amount available |
7,000
|
7,000
|
|
|
7,000
|
|
7,000
|
|
|
| Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds |
2,600
|
3,500
|
|
|
2,600
|
|
3,500
|
|
|
| FHLB advances, line of credit |
900
|
500
|
|
|
900
|
|
500
|
|
|
| Federal Home Loan Bank advances (includes both long-term and short-term) |
2,646
|
3,541
|
|
$ 988
|
2,646
|
|
3,541
|
514
|
988
|
| Federal Home Loan Bank, Advances, Activity for Year [Abstract] |
|
|
|
|
|
|
|
|
|
| Maximum outstanding at any month end |
2,646
|
|
$ 2,198
|
|
3,557
|
$ 2,198
|
3,541
|
1,300
|
2,908
|
| Average outstanding balance |
2,460
|
|
1,828
|
|
2,841
|
1,497
|
1,811
|
939
|
2,915
|
| Average remaining borrowing capacity |
$ 983
|
|
$ 1,503
|
|
$ 843
|
$ 1,697
|
$ 1,611
|
$ 1,947
|
$ 735
|
| Weighted average interest rate (as a percent) |
1.42%
|
|
0.90%
|
|
1.25%
|
0.97%
|
1.00%
|
0.23%
|
3.22%
|
| Long-term fixed rate advances |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Long-term Federal Home Loan Bank advances |
$ 125
|
175
|
|
|
$ 125
|
|
$ 175
|
|
|
| Other liabilities |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Notional Amount |
14,513
|
4,013
|
|
|
14,513
|
|
4,013
|
$ 3,865
|
|
| Interest Rate Swaps, FHLB Advances | Designated as Hedging Instrument | Other liabilities |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Notional Amount |
825
|
825
|
|
|
825
|
|
825
|
|
|
| Long-term LIBOR adjustable advances |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank advances (includes both long-term and short-term) |
1,025
|
825
|
|
0
|
1,025
|
|
$ 825
|
$ 0
|
$ 0
|
| Three Month LIBOR |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds |
1,000
|
|
|
|
$ 1,000
|
|
|
|
|
| Debt instrument, variable interest rate term (in months) |
|
|
|
|
3 months
|
|
3 months
|
3 months
|
|
| FHLB Advances, Interest Rate Reset Period (in months) |
|
|
|
|
3 months
|
|
3 months
|
|
|
| FHLB Advances, Prepayment Notification Period (in months) |
|
|
|
|
3 months
|
|
3 months
|
|
|
| FHLB Advances, Initial Lockout Period (in months) |
|
|
|
|
12 months
|
|
12 months
|
|
|
| Long-term fixed rate advances |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank advances (includes both long-term and short-term) |
$ 552
|
600
|
|
0
|
$ 552
|
|
$ 600
|
$ 300
|
$ 0
|
| Federal Home Loan Bank Advances |
|
|
|
|
|
|
|
|
|
| Federal Home Loan Bank, Advances [Line Items] |
|
|
|
|
|
|
|
|
|
| Payments for Federal Home Loan Bank advances |
|
375
|
|
2,900
|
|
|
|
|
|
| Gain (loss) on extinguishment of debt |
|
$ 3
|
|
$ (178)
|
|
|
|
|
|