Fair Value Measurements

6 Months Ended

Jun. 30, 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 six months ended June 30, 2023.

Financial instruments measured at fair value on a recurring basis:


	As of June 30, 2023						As of December 31, 2022
(in thousands)	Total		Level 1		Level 2		Total		Level 1		Level 2
Cash equivalents
Money market funds	$	34,211	$	34,211	$	—	$	88,073	$	88,073	$	—
Commercial paper	25,946		—		25,946		50,791		—		50,791
Municipal debt securities	7,998		—		7,998		8,599		—		8,599

Federal agency debt securities	2,296		—		2,296		—		—		—

Total cash equivalents	70,451		34,211		36,240		147,463		88,073		59,390
Short-term
Commercial paper	367,982		—		367,982		421,279		—		421,279
Federal agency debt securities	219,032		—		219,032		107,222		—		107,222
Corporate debt securities	189,954		—		189,954		166,136		—		166,136
US Treasury Bonds	30,713		—		30,713		—		—		—
Municipal debt securities	17,486		—		17,486		30,426		—		30,426
Total short-term	825,167		—		825,167		725,063		—		725,063
Long-term
Federal agency debt securities	32,921		—		32,921		20,050		—		20,050
Corporate debt securities	22,915		—		22,915		35,688		—		35,688

Municipal debt securities	13,460		—		13,460		7,580		—		7,580

Total long-term	69,296		—		69,296		63,318		—		63,318
Total financial instruments	$	964,914	$	34,211	$	930,703	$	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 June 30, 2023				As of December 31, 2022
(in thousands)	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Hierarchy Level
Fair Value of Notes Payable	$	1,711,807	$	1,719,626	$	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.