Investments and Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financial Assets
Assets, Fair Value Disclosure	$ 165,364	$ 206,005
Commercial paper
Financial Assets
Marketable investments	5,975	20,276
U.S. treasury
Financial Assets
Marketable investments	14,003	14,387
U.S. agency and government sponsored securities
Financial Assets
Marketable investments	8,313	11,535
U.S. states and municipalities
Financial Assets
Marketable investments	29,475	39,386
Corporate bonds
Financial Assets
Marketable investments	88,369	109,912
Commercial paper
Financial Assets
Cash equivalents	4,389
Money market funds
Financial Assets
Cash equivalents	14,840	10,509
Level 1
Financial Assets
Assets, Fair Value Disclosure	28,843	24,896
Level 1 | Commercial paper
Financial Assets
Marketable investments	0	0
Level 1 | U.S. treasury
Financial Assets
Marketable investments	14,003	14,387
Level 1 | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	0	0
Level 1 | U.S. states and municipalities
Financial Assets
Marketable investments	0	0
Level 1 | Corporate bonds
Financial Assets
Marketable investments	0	0
Level 1 | Commercial paper
Financial Assets
Cash equivalents	0
Level 1 | Money market funds
Financial Assets
Cash equivalents	14,840	10,509
Level 2
Financial Assets
Assets, Fair Value Disclosure	136,521	181,109
Level 2 | Commercial paper
Financial Assets
Marketable investments	5,975	20,276
Level 2 | U.S. treasury
Financial Assets
Marketable investments	0	0
Level 2 | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	8,313	11,535
Level 2 | U.S. states and municipalities
Financial Assets
Marketable investments	29,475	39,386
Level 2 | Corporate bonds
Financial Assets
Marketable investments	88,369	109,912
Level 2 | Commercial paper
Financial Assets
Cash equivalents	4,389
Level 2 | Money market funds
Financial Assets
Cash equivalents	0	0
Level 3
Financial Assets
Assets, Fair Value Disclosure	0	0
Level 3 | Commercial paper
Financial Assets
Marketable investments	0	0
Level 3 | U.S. treasury
Financial Assets
Marketable investments	0	0
Level 3 | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	0	0
Level 3 | U.S. states and municipalities
Financial Assets
Marketable investments	0	0
Level 3 | Corporate bonds
Financial Assets
Marketable investments	0	0
Level 3 | Commercial paper
Financial Assets
Cash equivalents	0
Level 3 | Money market funds
Financial Assets
Cash equivalents	$ 0	$ 0