Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Quarterly Financial Information Disclosure [Abstract] | |||||||||||
| Total revenue | $ 14,055 | $ 17,046 | $ 13,083 | $ 16,025 | $ 35,421 | $ 41,757 | $ 28,851 | $ 29,039 | $ 60,209 | $ 135,068 | $ 205,825 |
| Total operating expenses | 144,611 | 146,861 | 156,792 | 157,665 | 188,452 | 127,575 | 125,866 | 106,441 | 605,929 | 548,334 | 475,181 |
| Loss from operations | $ (130,556) | $ (129,815) | $ (143,709) | $ (141,640) | $ (153,031) | $ (85,818) | $ (97,015) | $ (77,402) | $ (545,720) | $ (413,266) | $ (269,356) |
| Net loss per share attributable to common stockholders, basic and diluted (usd per share) | $ (0.37) | $ (0.37) | $ (0.41) | $ (0.40) | $ (1.14) | $ (1.32) | $ (1.43) | $ (1.16) | $ (1.55) | $ (4.95) | $ (4.18) |
| Accounting Standards Update 2016-02 | |||||||||||
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |||||||||||
| New accounting pronouncement or change in accounting principle, effect of change on operating results | $ 1,000 | $ 200 | $ 200 | ||||||||