Fair Value Measurements - Fair Value of Contingent Consideration Liabilities (Details) - USD ($) |
3 Months Ended | 12 Months Ended | |||||
|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | |||||||
| Balance at December 31, 2018 | $ 0 | $ 0 | |||||
| Contingent consideration related to acquisition of Exonics | 172,041,000 | ||||||
| Increase in fair value of contingent consideration | $ 1,500,000 | $ 2,959,000 | $ 0 | $ 0 | 4,459,000 | $ 0 | $ 0 |
| Balance at December 31, 2019 | 176,500,000 | 176,500,000 | 0 | ||||
| Intangible asset | $ 400,000,000.0 | $ 400,000,000.0 | $ 0 | ||||