Acquisitions - Exonics Therapeutics (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Jul. 16, 2019 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Business Acquisition [Line Items] | |||
| Fair value of contingent development and regulatory payments | $ 172,041,000 | ||
| Goodwill | 1,002,158,000 | $ 50,384,000 | |
| Intangible asset | $ 400,000,000.0 | $ 0 | |
| Exonics Therapeutics | |||
| Business Acquisition [Line Items] | |||
| Upfront payment (adjusted for customary working capital adjustments) | $ 266,315,000 | ||
| Fair value of contingent development and regulatory payments | 172,041,000 | ||
| Total purchase price | 438,356,000 | ||
| Cash and cash equivalents | 19,535,000 | ||
| Goodwill | 397,141,000 | ||
| Intangible asset | 13,000,000 | ||
| Net other assets | $ 8,680,000 |