Fair Value Measurements Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 488,689	$ 579,105
US Government Securities, at Carrying Value	8,032	5,782
Municipal bonds	22,749	26,009
Total	519,470	610,896
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	8,056	5,783
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	24	1
Debt Securities, Available-for-sale	8,032	5,782
Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	22,783	26,017
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	36	8
Debt Securities, Available-for-sale	22,749	26,009
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	488,689	579,105
US Government Securities, at Carrying Value	8,032	5,782
Municipal bonds	0	0
Total	496,721	584,887
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
US Government Securities, at Carrying Value	0	0
Municipal bonds	22,749	26,009
Total	$ 22,749	$ 26,009