MBS (Details 2) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013 Security		Sep. 30, 2012		Sep. 30, 2013 Security		Sep. 30, 2012
Fair Value
Less than 12 months	$ 2,904,870,000				$ 2,904,870,000
12 months or more	205,632,000				205,632,000
Total	3,110,502,000				3,110,502,000
Unrealized Losses
Less than 12 months					68,725,000
12 months or more					7,695,000
Total					76,420,000
Number of Securities
Less than 12 months (in security)	291				291
12 months or more (in security)	47				47
OTTI charges recorded
Total OTTI losses	0		0		0		(879,000)
OTTI reclassified from OCI	0		0		0		(321,000)
Net Impairment Losses Recognized in Earnings	0		0		0		(1,200,000)
Roll-forward of the credit loss component of OTTI
Credit loss component of OTTI at beginning of period	36,115,000				36,115,000
Additions for credit related OTTI not previously recognized	0				0
Subsequent additional credit related OTTI recorded	0				0
Credit loss component of OTTI at end of period	36,115,000				36,115,000
Significant inputs considered and assumptions made in determining the measurement of the component of OTTI recorded in earnings
Number of days considered to classify loans delinquent					60 days
AOCI from MBS:
Unrealized gain on MBS at beginning of period	700,871,000		296,007,000		824,808,000		55,491,000
Unrealized gain/(loss) on Agency MBS, net	15,469,000		61,999,000		(152,302,000)		47,169,000
Unrealized gain on Non-Agency MBS, net	16,381,000		409,742,000		62,455,000		666,287,000
Reclassification adjustment for MBS sales included in net income	(15,158,000)		(3,130,000)		(17,398,000)		(5,529,000)
Reclassification adjustment for OTTI included in net income	0		0		0		1,200,000
Change in AOCI from MBS	16,692,000		468,611,000		(107,245,000)		709,127,000
Balance at end of period	717,563,000		764,618,000		717,563,000		764,618,000
Sales of MBS
Gross gains on sale of MBS	13,680,000		4,279,000		19,678,000		7,232,000
Agency MBS
Fair Value
Less than 12 months	2,572,532,000				2,572,532,000
12 months or more	162,509,000				162,509,000
Total	2,735,041,000				2,735,041,000
Unrealized Losses
Less than 12 months					62,500,000
12 months or more					5,151,000
Total					67,651,000
Number of Securities
Less than 12 months (in security)	254				254
12 months or more (in security)	35				35
Sales of MBS
Amount of MBS sold			66,000,000				137,100,000
Gross gains on sale of MBS			4,300,000				7,200,000
MBS Interest Income
Coupon interest	51,997,000		61,978,000		163,986,000		187,963,000
Effective yield adjustment	(15,839,000)	[1]	(14,780,000)	[1]	(47,004,000)	[1]	(37,915,000)	[1]
Interest on mortgage backed securities	36,158,000		47,198,000		116,982,000		150,048,000
Agency MBS | Fannie Mae.
Fair Value
Less than 12 months	1,796,814,000				1,796,814,000
12 months or more	119,958,000				119,958,000
Total	1,916,772,000				1,916,772,000
Unrealized Losses
Less than 12 months					38,545,000
12 months or more					3,425,000
Total					41,970,000
Number of Securities
Less than 12 months (in security)	154				154
12 months or more (in security)	29				29
Agency MBS | Freddie Mac.
Fair Value
Less than 12 months	775,718,000				775,718,000
12 months or more	42,551,000				42,551,000
Total	818,269,000				818,269,000
Unrealized Losses
Less than 12 months					23,955,000
12 months or more					1,726,000
Total					25,681,000
Number of Securities
Less than 12 months (in security)	100				100
12 months or more (in security)	6				6
Non-Agency MBS
Fair Value
Less than 12 months	332,338,000				332,338,000
12 months or more	43,123,000				43,123,000
Total	375,461,000				375,461,000
Unrealized Losses
Less than 12 months					6,225,000
12 months or more					2,544,000
Total					8,769,000
Number of Securities
Less than 12 months (in security)	37				37
12 months or more (in security)	12				12
Changes in the components of the purchase discount on Non-Agency MBS
MBS linked transactions purchase discount designated as credit reserve reallocated to accretable purchase discount			54,000		129,000
MBS linked transactions purchase discount designated as accretable purchase discount reallocated to Credit Reserves							575,000
Sales of MBS
Amount of MBS sold	102,200,000				118,200,000
Gross gains on sale of MBS	13,700,000				19,700,000
MBS Interest Income
Coupon interest	62,802,000		69,139,000		196,688,000		196,144,000
Effective yield adjustment	19,501,000	[2]	8,760,000	[2]	48,128,000	[2]	27,913,000	[2]
Interest on mortgage backed securities	82,303,000		77,899,000		244,816,000		224,057,000
Non-Agency MBS | Weighted average
OTTI, Significant Inputs and Assumptions
OTTI, Significant Inputs and Assumptions, Credit Enhancement	0.00%	[3],[4],[5]	0.00%	[3],[4],[5]	0.00%	[3],[4],[5]	3.26%	[3],[4],[5]
OTTI, Significant Inputs and Assumptions, Projected CPR	0.00%	[4],[5],[6]	0.00%	[4],[5],[6]	0.00%	[4],[5],[6]	9.90%	[4],[5],[6]
OTTI, Significant Inputs and Assumptions, Projected Loss Severity	0.00%	[4],[5],[7]	0.00%	[4],[5],[7]	0.00%	[4],[5],[7]	55.50%	[4],[5],[7]
OTTI, Significant Inputs and Assumptions, 60 or More Days Delinquent	0.00%	[4],[5],[8]	0.00%	[4],[5],[8]	0.00%	[4],[5],[8]	24.40%	[4],[5],[8]
Non-Agency MBS | Low end of range
OTTI, Significant Inputs and Assumptions
OTTI, Significant Inputs and Assumptions, Credit Enhancement	0.00%	[3],[4],[9]	0.00%	[3],[4],[9]	0.00%	[3],[4],[9]	0.00%	[3],[4],[9]
OTTI, Significant Inputs and Assumptions, Projected CPR	0.00%	[4],[6],[9]	0.00%	[4],[6],[9]	0.00%	[4],[6],[9]	9.10%	[4],[6],[9]
OTTI, Significant Inputs and Assumptions, Projected Loss Severity	0.00%	[4],[7],[9]	0.00%	[4],[7],[9]	0.00%	[4],[7],[9]	45.90%	[4],[7],[9]
OTTI, Significant Inputs and Assumptions, 60 or More Days Delinquent	0.00%	[4],[8],[9]	0.00%	[4],[8],[9]	0.00%	[4],[8],[9]	18.20%	[4],[8],[9]
Non-Agency MBS | High end of range
OTTI, Significant Inputs and Assumptions
OTTI, Significant Inputs and Assumptions, Credit Enhancement	0.00%	[3],[4],[9]	0.00%	[3],[4],[9]	0.00%	[3],[4],[9]	16.50%	[3],[4],[9]
OTTI, Significant Inputs and Assumptions, Projected CPR	0.00%	[4],[6],[9]	0.00%	[4],[6],[9]	0.00%	[4],[6],[9]	13.30%	[4],[6],[9]
OTTI, Significant Inputs and Assumptions, Projected Loss Severity	0.00%	[4],[7],[9]	0.00%	[4],[7],[9]	0.00%	[4],[7],[9]	60.00%	[4],[7],[9]
OTTI, Significant Inputs and Assumptions, 60 or More Days Delinquent	0.00%	[4],[8],[9]	0.00%	[4],[8],[9]	0.00%	[4],[8],[9]	32.40%	[4],[8],[9]
Non-Agency MBS | Discount Designated as Credit Reserve and OTTI
Changes in the components of the purchase discount on Non-Agency MBS
Balance at beginning of period	(1,264,971,000)	[10]	(1,440,752,000)	[11]	(1,380,506,000)	[10]	(1,228,766,000)	[11]
Accretion of discount	0	[10]	0	[11]	0	[10]	0	[11]
Realized credit losses	48,642,000	[10]	49,314,000	[11]	137,324,000	[10]	107,229,000	[11]
Purchases	(851,000)	[10]	(122,266,000)	[11]	(74,238,000)	[10]	(370,649,000)	[11]
Sales	27,178,000	[10]	0	[11]	38,150,000	[10]	0	[11]
Reclassification adjustment for OTTI					0	[10]	866,000	[11]
Net impairment losses recognized in earnings					0	[10]	(1,200,000)	[11]
Unlinking of Linked Transactions	0	[10]	0	[11]	0	[10]	(38,662,000)	[11]
Transfers/release of credit reserve	71,010,000	[10]	54,053,000	[11]	160,278,000	[10]	71,531,000	[11]
Balance at end of period	(1,118,992,000)	[10]	(1,459,651,000)	[11]	(1,118,992,000)	[10]	(1,459,651,000)	[11]
Non-Agency MBS | Accretable Discount
Changes in the components of the purchase discount on Non-Agency MBS
Balance at beginning of period	(396,581,000)	[10],[12]	(265,137,000)	[11],[12]	(371,626,000)	[10],[12]	(250,479,000)	[11],[12]
Accretion of discount	19,556,000	[10],[12]	8,816,000	[11],[12]	48,305,000	[10],[12]	28,107,000	[11],[12]
Realized credit losses	0	[10],[12]	0	[11],[12]	0	[10],[12]	0	[11],[12]
Purchases	879,000	[10],[12]	4,554,000	[11],[12]	30,533,000	[10],[12]	(3,883,000)	[11],[12]
Sales	4,248,000	[10],[12]	0	[11],[12]	10,158,000	[10],[12]	0	[11],[12]
Reclassification adjustment for OTTI					0	[10],[12]	(866,000)	[11],[12]
Net impairment losses recognized in earnings					0	[10],[12]	0	[11],[12]
Unlinking of Linked Transactions	0	[10],[12]	(2,256,000)	[11],[12]	0	[10],[12]	(9,424,000)	[11],[12]
Transfers/release of credit reserve	(71,010,000)	[10],[12]	(54,053,000)	[11],[12]	(160,278,000)	[10],[12]	(71,531,000)	[11],[12]
Balance at end of period	(442,908,000)	[10],[12]	(308,076,000)	[11],[12]	(442,908,000)	[10],[12]	(308,076,000)	[11],[12]
Non-Agency MBS | Rated A
Fair Value
Less than 12 months	0				0
12 months or more	681,000				681,000
Total	681,000				681,000
Unrealized Losses
Less than 12 months					0
12 months or more					32,000
Total					32,000
Number of Securities
Less than 12 months (in security)	0				0
12 months or more (in security)	1				1
Non-Agency MBS | Rated BBB
Fair Value
Less than 12 months	6,880,000				6,880,000
12 months or more	18,421,000				18,421,000
Total	25,301,000				25,301,000
Unrealized Losses
Less than 12 months					74,000
12 months or more					786,000
Total					860,000
Number of Securities
Less than 12 months (in security)	1				1
12 months or more (in security)	3				3
Non-Agency MBS | Rated BB
Fair Value
Less than 12 months	0				0
12 months or more	2,022,000				2,022,000
Total	2,022,000				2,022,000
Unrealized Losses
Less than 12 months					0
12 months or more					221,000
Total					221,000
Number of Securities
Less than 12 months (in security)	0				0
12 months or more (in security)	3				3
Non-Agency MBS | Rated B
Fair Value
Less than 12 months	6,690,000				6,690,000
12 months or more	0				0
Total	6,690,000				6,690,000
Unrealized Losses
Less than 12 months					46,000
12 months or more					0
Total					46,000
Number of Securities
Less than 12 months (in security)	1				1
12 months or more (in security)	0				0
Non-Agency MBS | Rated CCC
Fair Value
Less than 12 months	55,983,000				55,983,000
12 months or more	21,998,000				21,998,000
Total	77,981,000				77,981,000
Unrealized Losses
Less than 12 months					1,060,000
12 months or more					1,473,000
Total					2,533,000
Number of Securities
Less than 12 months (in security)	7				7
12 months or more (in security)	4				4
Non-Agency MBS | Rated CC
Fair Value
Less than 12 months	1,594,000				1,594,000
12 months or more	0				0
Total	1,594,000				1,594,000
Unrealized Losses
Less than 12 months					32,000
12 months or more					0
Total					32,000
Number of Securities
Less than 12 months (in security)	2				2
12 months or more (in security)	0				0
Non-Agency MBS | Rated C
Fair Value
Less than 12 months	8,951,000				8,951,000
12 months or more	0				0
Total	8,951,000				8,951,000
Unrealized Losses
Less than 12 months					181,000
12 months or more					0
Total					181,000
Number of Securities
Less than 12 months (in security)	1				1
12 months or more (in security)	0				0
Non-Agency MBS | Unrated and D-rated
Fair Value
Less than 12 months	252,240,000				252,240,000
12 months or more	1,000				1,000
Total	252,241,000				252,241,000
Unrealized Losses
Less than 12 months					4,832,000
12 months or more					32,000
Total					$ 4,864,000
Number of Securities
Less than 12 months (in security)	25				25
12 months or more (in security)	1				1

[1] Includes amortization of premium paid net of accretion of purchase discount. For Agency MBS, interest income is recorded at an effective yield, which reflects net premium amortization based on actual prepayment activity.

[2] The effective yield adjustment is the difference between the net income calculated using the net yield, which is based on management’s estimates of future cash flows for Non-Agency MBS, less the current coupon yield.

[3] Represents a level of protection for these securities, expressed as a percentage of total current underlying loan balance.

[4] Information provided is based on loans for all groups that provide credit enhancement for MBS with credit enhancement. If an MBS no longer has credit enhancement, information provided is based on loans for the individual group owned by the Company.

[5] Calculated by weighting the relevant input/assumptions for each individual security by current outstanding face of the security.

[6] CPR - conditional prepayment rate.

[7] Projected loss severity represents the projected amount of loss realized on liquidated properties as a percentage of the principal balance.

[8] Includes, for each security, underlying loans 60 or more days delinquent, foreclosed loans and other real estate owned.

[9] Represents the range of inputs/assumptions based on individual securities.

[10] During the three months ended September 30, 2013, the Company did not reallocate any purchase discount designated as Credit Reserve to accretable purchase discount on Non-Agency MBS underlying Linked Transactions. The Company reallocated $54,000 of purchase discount designated as Credit Reserve to accretable purchase discount on Non-Agency MBS underlying Linked Transactions during the three months ended September 30, 2012.

[11] During the nine months ended September 30, 2013, the Company reallocated $129,000 of purchase discount designated as Credit Reserve to accretable purchase discount on Non-Agency MBS underlying Linked Transactions. In addition, the Company reallocated $575,000 of purchase discount designated as accretable purchase discount to Credit Reserve on Non-Agency MBS underlying Linked Transactions during the nine months ended September 30, 2012

[12] Together with coupon interest, accretable purchase discount is recognized as interest income over the life of the security.