Commitments and Contingencies - Textual (Details)		1 Months Ended			3 Months Ended		6 Months Ended		12 Months Ended	24 Months Ended
	Aug. 11, 2016 claim	Apr. 30, 2017 USD ($)	Feb. 28, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2017 USD ($) ft² building	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) ft² building	Jun. 30, 2016 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2012 USD ($)
Commitments and Contingencies [Line Items]
Incentive from lessor				$ 1,300,000	$ 1,100,000		$ 1,100,000
Asset retirement obligations				400,000	400,000		400,000
Noncurrent restricted cash				$ 1,624,000	1,576,000		1,576,000
Rent expense					1,000,000	$ 800,000	1,900,000	$ 1,700,000
Capital lease obligations incurred		$ 300,000	$ 400,000
Capital leases, term of contract		3 years	3 years	3 years
Operating lease, sublease rentals					300,000	$ 300,000	700,000	$ 500,000
Operating lease, future minimum sublease rentals					$ 2,200,000		$ 2,200,000
Claims dismissed | claim	5
Fifth Amendment [Member]
Commitments and Contingencies [Line Items]
Payments for capital improvements									$ 3,600,000
Tenant reimbursements										$ 3,100,000
Headquarters, Redwood City [Member] | Sixth Amendment [Member]
Commitments and Contingencies [Line Items]
Lease area space occupancy (square feet) | ft²					107,200		107,200
Number of buildings leased | building					4		4
Minimum [Member]
Commitments and Contingencies [Line Items]
Expiration date of lease							Jan. 31, 2020
Maximum [Member]
Commitments and Contingencies [Line Items]
Expiration date of lease							Jan. 31, 2022
Standby Letters of Credit [Member]
Commitments and Contingencies [Line Items]
Noncurrent restricted cash				$ 800,000	$ 700,000		$ 700,000
Indemnification Agreement [Member]
Commitments and Contingencies [Line Items]
Loss contingency accrual				$ 0	$ 0		$ 0