Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value, Measurement Inputs, Disclosure

Fair Value Measurements

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, 2020.

Financial instruments measured at fair value on a recurring basis:



	June 30, 2020						December 31, 2019
(in thousands)	Total		Level 1		Level 2		Total		Level 1		Level 2
Cash equivalents
Money market funds	$	107,066	$	107,066	$	—	$	42,653	$	42,653	$	—
Municipal debt securities	32,575		—		32,575		1,202		—		1,202
Commercial paper	30,351		—		30,351		5,807		—		5,807
Federal agency debt securities	7,909		—		7,909		—		—		—
Total cash equivalents	177,901		107,066		70,835		49,662		42,653		7,009
Short-term
Commercial paper	208,194		—		208,194		161,286		—		161,286
Corporate debt securities	128,344		—		128,344		145,975		—		145,975
Municipal debt securities	36,892		—		36,892		12,237		—		12,237
Federal agency debt securities	14,375		—		14,375		13,515		—		13,515
US Treasury bonds	3,059		—		3,059		2,915		—		2,915
Total short-term	390,864		—		390,864		335,928		—		335,928
Long-term
Corporate debt securities	—		—		—		15,396		—		15,396
US Treasury bonds	—		—		—		146		—		146
Total long-term	—		—		—		15,542		—		15,542
Total financial instruments	$	568,765	$	107,066	$	461,699	$	401,132	$	42,653	$	358,479

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, including current maturities and without reduction for related costs, are as follows:



	June 30, 2020				December 31, 2019
(in thousands)	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Hierarchy Level
Non-publicly held debt	$	1,411,188	$	1,294,748	$	1,329,882	$	1,140,232	3

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