Schedule of Notional Amounts of Derivative Positions (Details) - USD ($) $ in Thousands |
3 Months Ended |
9 Months Ended |
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
$ 26,141,370
|
$ 27,401,335
|
$ 21,998,381
|
$ 48,115,523
|
Derivative, Notional Amount, Additions |
(22,872)
|
(6,930,287)
|
(31,254,394)
|
(30,475,551)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
4,055,594
|
6,014,042
|
31,189,871
|
50,273,494
|
Derivative, Notional Amount, Ending Balance |
22,062,904
|
28,317,580
|
22,062,904
|
28,317,580
|
Derivative, Average Notional Amount |
(20,642,679)
|
(27,222,458)
|
(22,701,140)
|
(32,531,397)
|
Gain (Loss) on Sale of Derivatives |
(154,155)
|
(78,283)
|
(146,046)
|
(160,665)
|
Inverse Interest-Only Securities [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
834,866
|
1,049,743
|
932,037
|
1,168,226
|
Derivative, Notional Amount, Additions |
0
|
0
|
0
|
(12,563)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
50,043
|
63,842
|
147,214
|
194,888
|
Derivative, Notional Amount, Ending Balance |
784,823
|
985,901
|
784,823
|
985,901
|
Derivative, Average Notional Amount |
(813,045)
|
(1,020,199)
|
(860,920)
|
(1,081,376)
|
Gain (Loss) on Sale of Derivatives |
0
|
0
|
0
|
64
|
Interest Rate Swap [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
13,697,000
|
16,225,523
|
14,268,806
|
18,584,000
|
Derivative, Notional Amount, Additions |
(4,451,430)
|
(5,280,000)
|
(16,553,456)
|
(22,393,227)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
1,203,000
|
7,480,000
|
13,876,832
|
26,951,704
|
Derivative, Notional Amount, Ending Balance |
16,945,430
|
14,025,523
|
16,945,430
|
14,025,523
|
Derivative, Average Notional Amount |
(14,497,913)
|
(15,371,175)
|
(14,751,923)
|
(16,753,347)
|
Gain (Loss) on Sale of Derivatives |
(39,369)
|
(24,948)
|
(33,067)
|
(92,816)
|
Credit Default Swap [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
25,000
|
125,000
|
125,000
|
125,000
|
Derivative, Notional Amount, Additions |
0
|
0
|
(10,000)
|
0
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
0
|
0
|
110,000
|
0
|
Derivative, Notional Amount, Ending Balance |
25,000
|
125,000
|
25,000
|
125,000
|
Derivative, Average Notional Amount |
(25,000)
|
(125,000)
|
(87,883)
|
(125,000)
|
Gain (Loss) on Sale of Derivatives |
0
|
0
|
412
|
0
|
Interest Rate Swaption [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
1,800,000
|
9,410,000
|
5,200,000
|
12,410,000
|
Derivative, Notional Amount, Additions |
(1,537,000)
|
0
|
(1,063,000)
|
(7,050,000)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
7,000
|
600,000
|
5,993,000
|
9,450,000
|
Derivative, Notional Amount, Ending Balance |
270,000
|
10,010,000
|
270,000
|
10,010,000
|
Derivative, Average Notional Amount |
(219,315)
|
(9,481,739)
|
(3,192,617)
|
(10,862,930)
|
Gain (Loss) on Sale of Derivatives |
(55,692)
|
(36,960)
|
(86,481)
|
(32,168)
|
Forward Contracts [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
337,000
|
1,024,000
|
297,000
|
1,325,000
|
Derivative, Notional Amount, Additions |
(5,622,000)
|
(468,000)
|
(1,186,000)
|
(11,330,000)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
5,370,000
|
2,274,000
|
300,000
|
13,437,000
|
Derivative, Notional Amount, Ending Balance |
589,000
|
782,000
|
589,000
|
782,000
|
Derivative, Average Notional Amount |
(1,051,989)
|
(343,272)
|
(239,493)
|
(729,916)
|
Gain (Loss) on Sale of Derivatives |
(18,819)
|
(13,615)
|
12,932
|
(38,461)
|
Options Held [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
8,897,000
|
0
|
0
|
2,000,000
|
Derivative, Notional Amount, Additions |
(2,269,000)
|
(1,000,000)
|
(13,166,000)
|
(1,250,000)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
6,697,000
|
0
|
8,697,000
|
2,250,000
|
Derivative, Notional Amount, Ending Balance |
4,469,000
|
1,000,000
|
4,469,000
|
1,000,000
|
Derivative, Average Notional Amount |
(5,607,728)
|
(163,043)
|
(3,091,679)
|
(183,150)
|
Gain (Loss) on Sale of Derivatives |
(26,955)
|
0
|
(28,303)
|
7,796
|
Treasury Lock [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
|
0
|
|
0
|
Derivative, Notional Amount, Additions |
|
0
|
|
(500,000)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
|
0
|
|
500,000
|
Derivative, Notional Amount, Ending Balance |
|
0
|
|
0
|
Derivative, Average Notional Amount |
|
0
|
|
(916)
|
Gain (Loss) on Sale of Derivatives |
|
0
|
|
(837)
|
Swap [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
|
0
|
|
14,000,000
|
Derivative, Notional Amount, Additions |
|
0
|
|
(6,000,000)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
|
0
|
|
20,000,000
|
Derivative, Notional Amount, Ending Balance |
|
0
|
|
0
|
Derivative, Average Notional Amount |
|
0
|
|
(3,018,315)
|
Gain (Loss) on Sale of Derivatives |
|
0
|
|
7,694
|
Total Return Swap [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
588,037
|
988,409
|
889,418
|
598,459
|
Derivative, Notional Amount, Additions |
(99,911)
|
(176,807)
|
(99,911)
|
(1,601,350)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
591,700
|
277,252
|
893,081
|
1,311,845
|
Derivative, Notional Amount, Ending Balance |
96,248
|
887,964
|
96,248
|
887,964
|
Derivative, Average Notional Amount |
(113,334)
|
(828,323)
|
(598,163)
|
(968,223)
|
Gain (Loss) on Sale of Derivatives |
(13,897)
|
(2,368)
|
(13,374)
|
(11,296)
|
Loan Purchase Commitments [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
636,467
|
626,660
|
286,120
|
554,838
|
Derivative, Notional Amount, Additions |
(315,787)
|
(941,480)
|
(1,548,027)
|
(3,048,411)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
890,851
|
1,066,948
|
1,772,744
|
3,102,057
|
Derivative, Notional Amount, Ending Balance |
61,403
|
501,192
|
61,403
|
501,192
|
Derivative, Average Notional Amount |
(418,333)
|
(576,251)
|
(357,448)
|
(634,356)
|
Gain (Loss) on Sale of Derivatives |
$ 577
|
(392)
|
$ 1,835
|
(766)
|
Short US Treasury Securities [Member] |
|
|
|
|
Derivative [Line Items] |
|
|
|
|
Derivative, Notional Amount, Beginning Balance |
|
0
|
|
0
|
Derivative, Notional Amount, Additions |
|
0
|
|
(50,000)
|
Derivative, Notional Amount, Settlement Termination Expiration or Exercise |
|
0
|
|
50,000
|
Derivative, Notional Amount, Ending Balance |
|
0
|
|
0
|
Derivative, Average Notional Amount |
|
0
|
|
0
|
Gain (Loss) on Sale of Derivatives |
|
$ 0
|
|
$ 125
|