Commitments and contingencies - Operating Leases (Details) - USD ($) $ in Thousands |
1 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Future minimum lease payments under operating leases | ||||
| 2016 | $ 6,224 | |||
| 2017 | 7,366 | |||
| 2018 | 7,269 | |||
| 2019 | 7,463 | |||
| 2020 | 7,068 | |||
| Thereafter | 44,374 | |||
| Total minimum lease payments | 79,764 | |||
| Rent expense | 3,700 | $ 1,400 | $ 800 | |
| Office Facility In San Francisco | New Leases | ||||
| Additional term of lease | 10 years | |||
| Lease term | 10 years | |||
| Security Deposit | $ 4,600 | |||
| Lease incentive in form of lease improvements | $ 5,200 | |||
| Incentive utilized | 0 | |||
| Future minimum lease payments under operating leases | ||||
| Total minimum lease payments | 72,000 | |||
| Other Noncurrent Assets [Member] | ||||
| Security Deposit | $ 1,500 | $ 1,400 | ||