Discontinued Operations (Details 1) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2014 sqft property		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014 sqft property	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2014 sqft
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Land And Improvements									$ 49,656,000									$ 49,656,000
Disposal Group, Including Discontinued Operation, Buildings and Improvements									209,594,000									209,594,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment									259,250,000									259,250,000
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Accumulated Depreciation									63,110,000									63,110,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Noncurrent									196,140,000									196,140,000
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net									269,000									269,000
Disposal Group, Including Discontinued Operation, Deferred Rent Receivable, Net									8,978,000									8,978,000
Disposal Group, Including Discontinued Operation, Deferred Leasing Costs and Acquisition-related Intangible Assets, Net									5,791,000									5,791,000
Disposal Group, Including Discontinued Operation, Prepaid and Other Assets, Current									1,922,000									1,922,000
Disposal Group, Including Discontinued Operation, Assets	8,211,000								213,100,000								8,211,000	213,100,000
Number of real estate properties	9																9
Net Rentable Area	14,096,617																14,096,617			79,000
Rental income																	7,206,000	31,984,000	49,689,000
Tenant reimbursements																	278,000	3,546,000	6,544,000
Other property income																	13,000	5,178,000	1,923,000
Total revenues																	7,497,000	40,708,000	58,156,000
Property expenses																	2,171,000	7,207,000	9,945,000
Real estate taxes																	692,000	3,523,000	5,696,000
Provision for bad debts																	0	0	(195,000)
Depreciation and amortization																	2,061,000	12,600,000	19,379,000
Total expenses																	4,924,000	23,330,000	34,825,000
Income from discontinued operations before net gain on dispositions of discontinued operations																	2,573,000	17,378,000	23,331,000
Net gain on dispositions of discontinued operations (Note 18)																	121,922,000	12,252,000	259,245,000
Total income from discontinued operations	12,013,000	[1],[2]	6,135,000	[1],[2]	15,289,000	[1],[2]	91,058,000	[1],[2]	18,009,000	[1],[2]	5,847,000	[1],[2]	3,161,000	[1],[2]	2,613,000	[1],[2]	124,495,000	29,630,000	282,576,000
Gain (Loss) on Disposition of Property Plant Equipment																	3,490,000
Net proceeds received from dispositions of operating properties and land (Note 18)																	427,544,000	21,178,000	263,572,000
Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities									1,153,000									1,153,000
Disposal Group, Including Discontinued Operation, Deferred Revenue and Acquisition-related Intangible Liabilities, Net									10,723,000									10,723,000
Disposal Group, Including Discontinued Operation, Advance Rents and Tenant Security Deposits									2,571,000									2,571,000
Disposal Group, Including Discontinued Operation, Liabilities	56,000								14,447,000								56,000	14,447,000
10850 Via Frontera San Diego CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Dispositions Sales Price																	33,100,000
Restricted cash [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds received from dispositions of operating properties and land (Note 18)																	59,200,000	32,200,000
Restricted cash [Member] | Released from Qualified Intermediary 2015 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds received from dispositions of operating properties and land (Note 18)																	59,200,000
Restricted cash [Member] | Released July 2014 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds received from dispositions of operating properties and land (Note 18)																		$ 32,200,000

[1] The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. The summation of the quarterly net income (loss) available to common stockholders per share does not equal the annual number reported on the consolidated statements of operations due to the Company's public offerings of common stock and its at-the-market stock offering programs that occurred during the years ended December 31, 2014 and 2013.

[2] All periods have been adjusted from amounts previously disclosed in our quarterly filings on Form 10-Q to reclassify amounts related to discontinued operations (see Note 18 “Discontinued Operations” for additional information).