Fair Value Measurements

9 Months Ended

Sep. 30, 2024

The Company utilizes the market approach to measure the fair value of its financial assets. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets. The assets classified as Level 2 primarily utilize quoted market prices or alternative pricing sources including transactions involving identical or comparable assets and models utilizing market observable inputs for valuation of these securities. No changes in valuation techniques or inputs occurred during the nine months ended September 30, 2024.

Financial instruments measured at fair value on a recurring basis:


	As of September 30, 2024						As of December 31, 2023
(in thousands)	Total		Level 1		Level 2		Total		Level 1		Level 2
Cash equivalents
Money market funds	$	54,649	$	54,649	$	—	$	33,613	$	33,613	$	—
Commercial paper	—		—		—		19,575		—		19,575
Municipal debt securities	—		—		—		7,848		—		7,848
Federal agency debt securities	—		—		—		8,201		—		8,201
US Treasury bonds	—		—		—		2,000		—		2,000

Total cash equivalents	54,649		54,649		—		71,237		33,613		37,624
Short-term
Corporate debt securities	253,431		—		253,431		210,982		—		210,982
Commercial paper	136,617		—		136,617		237,870		—		237,870
Federal agency debt securities	81,427		—		81,427		194,522		—		194,522
Municipal debt securities	14,751		—		14,751		13,914		—		13,914
Certificates of deposit	7,167		—		7,167		—		—		—
US Treasury Bonds	—		—		—		14,126		—		14,126
Total short-term	493,393		—		493,393		671,414		—		671,414
Long-term
Corporate debt securities	35,200		—		35,200		43,869		—		43,869
Federal agency debt securities	8,748		—		8,748		12,135		—		12,135

Municipal debt securities	1,342		—		1,342		—		—		—

Total long-term	45,290		—		45,290		56,004		—		56,004
Total financial instruments	$	593,332	$	54,649	$	538,683	$	798,655	$	33,613	$	765,042

None of the Company's debt is publicly held and as a result, the Company has determined the estimated fair value of these notes as Level 3 liabilities. Certain inputs used to determine fair value are unobservable and, therefore, could be sensitive to changes in inputs. The Company utilizes the discounted cash flow method to estimate the fair value of Level 3 debt.

The carrying value and estimated fair value of long-term debt, excluding finance leases, including current maturities and without reduction for related costs, are as follows:


	As of September 30, 2024				As of December 31, 2023
(in thousands)	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Hierarchy Level
Fair Value of Notes Payable	$	1,769,165	$	1,759,662	$	1,826,921	$	1,815,351	3

Due to their short-term nature, the carrying amounts of cash, restricted cash, accounts receivable and accounts payable approximate fair value.