Fair Value Measurements

3 Months Ended

Mar. 31, 2023

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 three months ended March 31, 2023.

Financial instruments measured at fair value on a recurring basis:


	As of March 31, 2023						As of December 31, 2022
(in thousands)	Total		Level 1		Level 2		Total		Level 1		Level 2
Cash equivalents
Money market funds	$	105,574	$	105,574	$	—	$	88,073	$	88,073	$	—
Commercial paper	70,727		—		70,727		50,791		—		50,791
Municipal debt securities	7,593		—		7,593		8,599		—		8,599



Total cash equivalents	183,894		105,574		78,320		147,463		88,073		59,390
Short-term
Commercial paper	373,285		—		373,285		421,279		—		421,279
US Treasury Bonds	23,457		—		23,457		—		—		—
Corporate debt securities	133,273		—		133,273		166,136		—		166,136
Municipal debt securities	12,157		—		12,157		30,426		—		30,426
Federal agency debt securities	148,421		—		148,421		107,222		—		107,222
Total short-term	690,593		—		690,593		725,063		—		725,063
Long-term
Federal agency debt securities	38,261		—		38,261		20,050		—		20,050
Corporate debt securities	22,904		—		22,904		35,688		—		35,688

Municipal debt securities	7,636		—		7,636		7,580		—		7,580

Total long-term	68,801		—		68,801		63,318		—		63,318
Total financial instruments	$	943,288	$	105,574	$	837,714	$	935,844	$	88,073	$	847,771

None of the Company's debt is publicly held and as a result, the Company has determined the estimated fair value of these notes to be Level 3. 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.

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 March 31, 2023				As of December 31, 2022
(in thousands)	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Hierarchy Level
Non-publicly held debt	$	1,655,092	$	1,636,067	$	1,626,114	$	1,561,939	3

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