Investment in Real Estate (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2012 LandParcel sqft acre IndustrialProperty	Mar. 31, 2011 IndustrialProperty	Dec. 31, 2011 IndustrialProperty
Investment in Real Estate (Textual) [Abstract]
Number of industrial properties acquired	1
Square Footage of Real Estate Property Acquired	400,000
Number of land parcel acquired	1
Purchase price of industrial property	$ 21,819
Purchase price of land parcel	1,224
Carrying value of mortgage loan assumed from acquisition	12,026
Cash Payment of Acquisition	8,324
Percentage of consideration paid of net fair value of acquisition	85.00%
Approximate gain due to the difference between carrying value and fair value of acquisition	776
Number of industrial properties Sold	3
Gross proceed from the sale of industrial properties	20,127
Gain on Sale of Real Estate	6,199	3,804
Gain on Sale of Real Estate Discontinued Operation	6,199	3,804
Number of industrial properties held for sale	15
Number of Land Parcels Held for Sale	1
Square Footage of Real Estate Property Held For Sale	2,700,000
Number of industrial properties included in discontinued operations		13	36
Notes receivable outstanding	47,511		55,502
Net discount of notes receivable outstanding	303		319
Fair value of notes receivable	51,754		58,734
Square Footage Of Real Estate Property Sold	700,000
Area of land parcel held for sale	55.9
Impairment reversal of industrial properties and land parcels	$ 304	$ 913
Number Of Industrial Properties Fair Value Measurements	1
Square Footage Industrial Properties Fair Value Measurements	10,000
Number Of Industrial Properties Other Fair Value Measurements	14
Square Footage Industrial Properties Other Fair Value Measurements	2,100,000
2003 Net Lease Joint Venture [Member]
Investment In Real Estate Other (Textual) [Abstract]
Ownership percentage purchased	85.00%

Area of land parcel held for sale.

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Business Acquisition Purchase Price Allocation Land Parcel

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Impairment reversal of industrial properties and land parcels.

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Number of industrial properties acquired.

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No definition available.

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Number Of Industrial Properties Fair Value Measurements

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Number Of Industrial Properties Other Fair Value Measurements

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Number of industrial properties Sold

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No definition available.

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Number of land parcel acquired.

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Number of operation and gain on sale of real estate for industrial property.

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No definition available.

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Number of operations of industrial properties held for sale.

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Number of Operations of Land Parcels Held for Sale

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This is the acquisition of equity for a property within the 2003 Net Lease Joint Venture.

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No definition available.

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Percentage of consideration paid of net fair value of acquisition.

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Sale of Industrial Properties of GLA Area in square Foot.

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Square Footage Industrial Properties Fair Value Measurements

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Square Footage Of Real Estate Property Acquired

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Square Footage Of Real Estate Property Held For Sale

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Square Footage Of Real Estate Property Sold

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Amount of cash paid to acquire the entity.

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Fair Value of the liabilities incurred by the acquirer to former owners of the acquiree, including the fair value of any contingent consideration. If liabilities transferred as consideration remain within the combined entity after the business combination (for example, because the assets or liabilities were transferred to the acquiree rather than to its former owners), and the acquirer therefore retains control of them; in that situation, the acquirer measures those liabilities at their carrying amounts immediately before the acquisition date.

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The amount of acquisition cost of a business combination allocated to land and building to be used in the normal course of business, not including assets that are held-for-sale.

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Pretax gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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- Definition

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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Amount of the excess of the fair value of acquired net assets over the cost of an acquired business after pro rata reduction of the amounts that otherwise would have been assigned to acquired assets except financial assets other than investments accounted for by the equity method, assets to be disposed of by sale, deferred tax assets, prepaid assets relating to pension and postretirement benefit plans, and other current assets. This amount is considered an extraordinary item and often referred to as negative goodwill. This element is gross of the related tax effect.

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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. An amount representing an agreement for an unconditional promise by the maker to pay the Company (holder) a definite sum of money at a future date(s).

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For an unclassified balance sheet, an amount representing an agreement for an unconditional promise by the maker to pay the Entity (holder) a definite sum of money at a future date, net of any write-downs taken for collection uncertainty on the part of the holder. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. This amount does not include amounts related to receivables held-for-sale.

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Disclosure of the unamortized amount of the discount on the note or receivable which is deducted from the face amount of the receivable or loan. The discount or premium is the difference between the present value and the face amount.

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