Commitments and Contingencies (Textual) (Details) ft² in Thousands	3 Months Ended		9 Months Ended		12 Months Ended	24 Months Ended
	Sep. 30, 2015 USD ($) ft²	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) ft²	Sep. 30, 2014 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 USD ($)
Commitments and Contingencies [Line Items]
Incentive from Lessor	$ 1,400,000		$ 1,400,000
Asset retirement obligations							$ 300,000
Accretion expense		$ 0		$ 0
Operating Leases, Rent Expense	900,000	900,000	2,600,000	2,500,000
Operating Leases, Rent Expense, Sublease Rentals	200,000	$ 100,000	500,000	$ 300,000
Estimated obligation payable	600,000		600,000
Fifth Amendment [Member]
Commitments and Contingencies [Line Items]
Payments for Capital Improvements					$ 3,600,000
Tenant Reimbursements						$ 3,100,000
Sixth Amendment [Member]
Commitments and Contingencies [Line Items]
Letters of credit	$ 700,000		$ 700,000				$ 700,000
Headquarters, Redwood City [Member] | Fifth Amendment [Member]
Commitments and Contingencies [Line Items]
Lease area space occupancy (square feet) | ft²	107		107
Chesapeake Space [Member]
Commitments and Contingencies [Line Items]
Expiration date of lease			Jan. 31, 2017
Penobscot Space, Building 2 Space, and Saginaw Space [Member] | Fifth Amendment [Member]
Commitments and Contingencies [Line Items]
Expiration date of lease			Jan. 31, 2020