Leases (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) ft²	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) ft² item	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease liabilities, current portion included in other accrued liabilities	$ 6,330		$ 6,330		$ 7,300
Operating lease liabilities, long-term portion	49,519		49,519		$ 21,246
Operating lease liabilities	$ 55,849		55,849
Noncash investing activities related to right-of-use assets			$ 30,100
Weighted average discount rate (as a percent)	7.49%		7.49%
Lease expense	$ 2,700	$ 1,900	$ 5,400	$ 3,900
Operating lease payments	$ 2,500	$ 2,200	$ 5,000	$ 4,400
Corporate Headquarters Lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	113,000		113,000
Number of office space locations | item			2
Term of lease	84 months		84 months
Renewal term of lease	5 years		5 years
"First Space" Sublease
Lessee, Lease, Description [Line Items]
Number of office space locations | ft²			88,000
"Second Space" Sublease
Lessee, Lease, Description [Line Items]
Number of office space locations | ft²			25,000
Corporate Headquarters Lease Amendment
Lessee, Lease, Description [Line Items]
Annual lease payment			$ 9,300
Term of lease	48 months		48 months
Austin TX, Long-term Lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	94,000		94,000
Term of lease	132 months		132 months
Tukwila, WA Lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	10,000		10,000
Term of lease	62 months		62 months
Renewal term of lease	5 years		5 years
San Carlos, CA Sublease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	25,879		25,879
Term of lease	48 months		48 months
Sublease receivable	$ 1,900		$ 1,900
San Carlos, CA Sublease Amendment
Lessee, Lease, Description [Line Items]
Noncash investing activities related to right-of-use assets			$ 29,700
San Carlos, CA Sublease Amendment | Rentable square feet surrendered in lease amendment
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	25,879		25,879
South San Francisco, CA Lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	11,395		11,395
Annual lease payment			$ 900
Term of lease	36 months		36 months