Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended					3 Months Ended	12 Months Ended
	Mar. 31, 2014 sqft	Mar. 31, 2013	Mar. 31, 2014 San Diego Properties, San Diego, CA [Member] building sqft		Mar. 31, 2014 10850 Via Frontera San Diego CA [Member]	Mar. 31, 2014 Restricted cash [Member]	Dec. 31, 2013 Restricted cash [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Real Estate Held-for-investment	$ 309,824	$ 0				$ 15,300	$ 32,200
Number of buildings			12	[1],[2]
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Undeveloped land and construction in progress					28,030
Prepaid expenses and other assets, net					242
Real estate and other assets held for sale, net					28,272
Accounts payable, accrued Liabilities and other liabilities					634
Liabilities of real estate assets held for sale					634
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Rental income	458	5,773
Tenant reimbursements	66	757
Other property income	9	3
Total revenues	533	6,533
Property expenses	87	968
Real estate taxes	69	673
Depreciation and amortization	0	2,690
Total expenses	156	4,331
Income from discontinued operations	377	2,202
Net gain on dispositions of discontinued operations	90,115	0
Total income from discontinued operations	$ 90,492	$ 2,202
Net Rentable Area	79,000		1,049,035	[1],[2]

[1] The San Diego Properties included the following: 10020 Pacific Mesa Boulevard, 6055 Lusk Avenue, 5010 and 5005 Wateridge Vista Drive, 15435 and 15445 Innovation Drive, and 15051, 15073, 15231, 15253, 15333 and 15378 Avenue of Science.

[2] These properties were held for sale as of December 31, 2013.