Fair Value Measurements - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	$ 5,786,241	$ 2,251,282
Liabilities, Carrying Amount	867,178	784,363
Cash			$ 4,300,000
Recurring basis | Carrying Amount | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	10,550
Liabilities, Carrying Amount		9,760
Recurring basis | Carrying Amount | Convertible senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	191,768
Liabilities, Carrying Amount		85,640
Recurring basis | Carrying Amount | Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	161,259
Liabilities, Carrying Amount		175,402
Recurring basis | Carrying Amount | Finance obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	182,791
Liabilities, Carrying Amount		181,553
Recurring basis | Carrying Amount | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	93,941
Recurring basis | Carrying Amount | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	99,171
Recurring basis | Carrying Amount | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Carrying Amount	306,089
Recurring basis | Total | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	10,550
Liabilities, Fair Value		9,760
Recurring basis | Total | Convertible senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	1,320,952
Liabilities, Fair Value		1,272,766
Recurring basis | Total | Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	161,259
Liabilities, Fair Value		175,402
Recurring basis | Total | Finance obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	182,791
Liabilities, Fair Value		181,553
Recurring basis | Total | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	93,941
Recurring basis | Total | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	99,171
Recurring basis | Total | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	306,089
Recurring basis | Significant Other Observable Inputs (Level 2) | Convertible senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	1,320,952
Liabilities, Fair Value		1,272,766
Recurring basis | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	93,941
Recurring basis | Significant Other Observable Inputs (Level 2) | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	99,171
Recurring basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	306,089
Recurring basis | Significant Other Unobservable Inputs (Level 3) | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	10,550
Liabilities, Fair Value		9,760
Recurring basis | Significant Other Unobservable Inputs (Level 3) | Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	161,259
Liabilities, Fair Value		175,402
Recurring basis | Significant Other Unobservable Inputs (Level 3) | Finance obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value	$ 182,791
Liabilities, Fair Value		$ 181,553