SECURED BORROWINGS (Details) - USD ($)
$ in Thousands |
3 Months Ended |
9 Months Ended |
Sep. 30, 2016 |
Dec. 31, 2015 |
Sep. 30, 2016 |
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Total collateral carrying amount |
$ 13,090,000
|
$ 13,540,000
|
$ 13,090,000
|
| Total borrowings outstanding |
12,431,839
|
12,958,394
|
$ 12,431,839
|
| Average borrowings for the effects of related derivatives held as cash flow hedges |
$ 12,731,035
|
$ 13,160,703
|
|
| Effective borrowing rate considering cash flow hedges |
0.84%
|
0.73%
|
0.84%
|
| Quarter-End Borrowing Rates Adjusted for Effects of Related Derivative Financial Instruments ("Derivatives") Held as Cash Flow Hedges [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Average borrowing rates |
0.86%
|
|
0.86%
|
| Year-End Borrowing Rates Adjusted for Effects of Related Derivatives Held as Cash Flow Hedges [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Average borrowing rates |
|
0.85%
|
|
| FHLB Advances [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Proceeds from sale of federal home loan bank stock |
$ 20,000
|
|
$ 50,000
|
| Investment in federal home loan bank stock |
10,000
|
|
10,000
|
| Collateral carrying amount for FHLB advances |
259,367
|
$ 2,956,908
|
259,367
|
| Accrued interest receivable |
1,039
|
11,422
|
1,039
|
| Borrowings outstanding for FHLB advance |
$ 250,000
|
$ 2,875,000
|
$ 250,000
|
| Average borrowing rates |
0.71%
|
0.43%
|
0.71%
|
| Agency Securities [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Collateral carrying amount |
$ 12,830,689
|
$ 10,579,208
|
$ 12,830,689
|
| Accrued interest receivable |
27,929
|
21,884
|
27,929
|
| Borrowings outstanding |
12,181,839
|
10,083,394
|
12,181,839
|
| Agency Securities [Member] | Borrowings with Maturities of 30 Days or Less [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Collateral carrying amount |
11,302,826
|
9,080,363
|
11,302,826
|
| Accrued interest receivable |
24,045
|
18,504
|
24,045
|
| Borrowings outstanding |
$ 10,741,746
|
$ 8,585,336
|
$ 10,741,746
|
| Average borrowing rates |
0.71%
|
0.67%
|
0.71%
|
| Agency Securities [Member] | Borrowings with Maturities of 31 to 90 Days [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Collateral carrying amount |
$ 1,365,926
|
$ 423,710
|
$ 1,365,926
|
| Accrued interest receivable |
2,881
|
861
|
2,881
|
| Borrowings outstanding |
$ 1,299,305
|
$ 346,177
|
$ 1,299,305
|
| Average borrowing rates |
0.72%
|
0.63%
|
0.72%
|
| Agency Securities [Member] | Borrowings with Maturities Greater than 90 Days [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Collateral carrying amount |
$ 160,250
|
$ 1,073,254
|
$ 160,250
|
| Accrued interest receivable |
1,003
|
2,519
|
1,003
|
| Borrowings outstanding |
$ 139,101
|
$ 1,150,000
|
$ 139,101
|
| Average borrowing rates |
0.92%
|
0.75%
|
0.92%
|
| Agency Securities [Member] | Similar Borrowings [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Collateral carrying amount |
$ 1,687
|
$ 1,881
|
$ 1,687
|
| Accrued interest receivable |
0
|
0
|
0
|
| Borrowings outstanding |
$ 1,687
|
$ 1,881
|
$ 1,687
|
| Average borrowing rates |
8.16%
|
8.12%
|
8.16%
|
| Agency Securities [Member] | FHLB Advances [Member] |
|
|
|
| Secured Borrowings, Including Interest Rate Hedging Activity [Line Items] |
|
|
|
| Total collateral carrying amount |
$ 13,090,056
|
$ 13,536,116
|
$ 13,090,056
|
| Accrued interest receivable |
28,968
|
33,306
|
28,968
|
| Total borrowings outstanding |
$ 12,431,839
|
$ 12,958,394
|
$ 12,431,839
|
| Average borrowing rates |
0.72%
|
0.62%
|
0.72%
|