Debt Securities (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2011	Sep. 30, 2011	Dec. 31, 2010
Mortgage-Backed Securities Available-for-Sale
Fair Value	$ 352,100,000	$ 352,100,000	$ 397,680,000
Mortgage-backed securities
Mortgage-Backed Securities Available-for-Sale
Purchase Amortized Cost	358,755,000	358,755,000
Credit OTTI	(2,621,000)	(2,621,000)
Recorded Amortized Cost	356,134,000	356,134,000	387,591,000
Non-Credit OTTI		(435,000)
Unrealized Gains	3,345,000	3,345,000	11,569,000
Unrealized Losses	(6,944,000)	(6,944,000)	(1,480,000)
Net Fair Value Adjustment	(4,034,000)	(4,034,000)	10,089,000
Fair Value	352,100,000	352,100,000	397,680,000
Description of variable rate basis		one-month LIBOR	one-month LIBOR
Effective variable rate basis (as a percent)	0.23944%	0.23944%	0.2606%
Fair value of securities not rated	177,500,000	177,500,000
Fair value of securities not rated where the obligors are special purpose entities	174,700,000	174,700,000
Loan to value ratio (as a percent)	31.00%
CMBS
Mortgage-Backed Securities Available-for-Sale
Purchase Amortized Cost	192,742,000	192,742,000
Recorded Amortized Cost	192,742,000	192,742,000	266,764,000
Unrealized Gains			9,074,000
Unrealized Losses	(5,035,000)	(5,035,000)	(683,000)
Net Fair Value Adjustment	(5,035,000)	(5,035,000)	8,391,000
Fair Value	187,707,000	187,707,000	275,155,000
Weighted Average Coupon (as a percent)	1.96%	1.96%	5.60%
Weighted Average Life (in years)		5.3	1.8
Description of variable rate basis		LIBOR	LIBOR
RMBS
Mortgage-Backed Securities Available-for-Sale
Purchase Amortized Cost	166,013,000	166,013,000
Credit OTTI	(2,621,000)	(2,621,000)
Recorded Amortized Cost	163,392,000	163,392,000	120,827,000
Non-Credit OTTI		(435,000)
Unrealized Gains	3,345,000	3,345,000	2,495,000
Unrealized Losses	(1,909,000)	(1,909,000)	(797,000)
Net Fair Value Adjustment	1,001,000	1,001,000	1,698,000
Fair Value	164,393,000	164,393,000	122,525,000
Weighted Average Coupon (as a percent)	0.87%	0.87%	0.60%
Weighted Average Life (in years)		4.2	1.3
Description of variable rate basis		LIBOR	LIBOR
Maximum investment in available-for-sale securities with aggregate expected modified durations of less than 12 months (as a percent)		10.00%
Cost of third party management		$ 500,000

Represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor as trading before the adjustments for other-than-temporary impairments are recognized in earnings.

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Represents the cost to execute trading of available-for-sale securities by a third party manager engaged by the entity.

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Represents the fair value disclosure of available-for-sale securities that are not rated and are issued by special purpose entities.

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Represents the fair value disclosure of available-for-sale securities not rated.

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The reference rate for the variable rate on available-for-sale securities, such as LIBOR or the US treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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Represents the percentage of the reference rate for the variable rate on available-for-sale securities as of the balance sheet date.

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Represents the weighted average coupon interest rate on available-for-sale securities.

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Represents the weighted average life of available-for-sale securities.

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Represents the maximum percentage of assets invested in a category of available-for-sale securities that is allocated for securities with expected modified durations of less than twelve months in the aggregate.

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Represents an unrealized loss on investment in debt or equity securities categorized as available-for-sale that is considered to be other-than-temporary.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

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This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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The net amount of gross unrealized gains (losses) for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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-Publisher FASB

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This item represents the gross unrealized losses for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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- Definition

This item represents the loan to collateral ratio of the underlying assets in the security, represented as a percentage, which was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are not other-than-temporarily impaired.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name FASB Staff Position (FSP)

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-Paragraph 17

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents securitized, pay-through debt securities collateralized by real estate mortgage loans (mortgages) as of the balance sheet date which have been categorized as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 7

-Paragraph 15

-IssueDate 2006-05-01

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Mortgage-Backed Securities

-URI http://asc.fasb.org/extlink&oid=6517959

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- Definition

The amount of other than temporary impairment (OTTI) loss on a debt security, categorized as Available-for-sale, related to factors other than credit losses when the entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis. This amount, which includes the portion attributable to the noncontrolling interest, if any, is a portion of the deduction from the total impairment losses of investments (before taxes) presented on the income statement; this amount is also referred to as the amount incurred by the reporting entity or the consolidated entity.

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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