Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
5.00% Convertible notes due 2027 | Unsecured Debt
Liabilities
Debt instrument, interest rate, stated percentage	5.00%
3.75% Convertible notes due 2023 | Unsecured Debt
Liabilities
Debt instrument, interest rate, stated percentage	3.75%
Level 1
Assets
Total cash equivalents	$ 196,679	$ 398,834
Liabilities
Total convertible notes payable	0	0
Level 1 | 5.00% Convertible notes due 2027
Liabilities
Total convertible notes payable	0	0
Level 1 | 3.75% Convertible notes due 2023
Liabilities
Total convertible notes payable	0	0
Level 1 | Money market funds
Assets
Total cash equivalents	196,679	398,834
Level 1 | Government-backed securities
Assets
Total cash equivalents	0	0
Level 1 | Treasury securities
Assets
Total cash equivalents	0	0
Level 1 | Corporate debt securities
Assets
Total cash equivalents	0	0
Level 1 | Agency securities
Assets
Total cash equivalents	0	0
Level 2
Assets
Total cash equivalents	259,941	400,536
Liabilities
Total convertible notes payable	131,292	494,900
Level 2 | 5.00% Convertible notes due 2027
Liabilities
Total convertible notes payable	131,292	172,789
Level 2 | 3.75% Convertible notes due 2023
Liabilities
Total convertible notes payable	0	322,111
Level 2 | Money market funds
Assets
Total cash equivalents	0	0
Level 2 | Government-backed securities
Assets
Total cash equivalents	200,000	296,000
Level 2 | Treasury securities
Assets
Total cash equivalents	36,913	0
Level 2 | Corporate debt securities
Assets
Total cash equivalents	23,028	0
Level 2 | Agency securities
Assets
Total cash equivalents	0	104,536
Level 3
Assets
Total cash equivalents	0	0
Liabilities
Total convertible notes payable	0	0
Level 3 | 5.00% Convertible notes due 2027
Liabilities
Total convertible notes payable	0	0
Level 3 | 3.75% Convertible notes due 2023
Liabilities
Total convertible notes payable	0	0
Level 3 | Money market funds
Assets
Total cash equivalents	0	0
Level 3 | Government-backed securities
Assets
Total cash equivalents	0	0
Level 3 | Treasury securities
Assets
Total cash equivalents	0	0
Level 3 | Corporate debt securities
Assets
Total cash equivalents	0	0
Level 3 | Agency securities
Assets
Total cash equivalents	$ 0	$ 0