Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements, Recurring and Nonrecurring

The carrying value and fair value, by fair value hierarchy, of the Company's financial instruments at June 30, 2022, and December 31, 2021, respectively, are as follows (in thousands):

			Fair Value Measurements at June 30, 2022
	Fair Value at June 30, 2022		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Recurring
Marketable securities
U.S. Treasury notes	$	161,438	$	161,438	$	—	$	—
U.S. Government-sponsored enterprise securities	136,193		136,193		—		—
Other
Liability-classified restricted stock awards	514		514		—		—
Total recurring	$	298,145	$	298,145	$	—	$	—

			Fair Value Measurements at December 31, 2021
	Fair Value at December 31, 2021		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Recurring
Marketable securities
U.S. Treasury notes	$	225,792	$	225,792	$	—	$	—
U.S. Government-sponsored enterprise securities	113,944		113,944		—		—
Other
Liability-classified restricted stock awards	894		894		—		—
Total recurring	$	340,630	$	340,630	$	—	$	—

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments

The carrying values and estimated fair values of the 2021 Bonds as of June 30, 2022, are summarized as follows:

	June 30, 2022
	Carrying Value		Estimated Fair Value
2021 Bonds	$	66,853	$	65,994