General

Schedule of accounts receivable, contract assets and contract liabilities

Accounts receivable, contract assets and contract liabilities consisted of the following (in thousands, except percentages):


	December 31,		September 30,
	2020		2021		$ Change		% Change
Accounts receivable	$	799,803	$	856,059	$	56,256		7.0%
Contract assets		3,566		8,114		4,548		127.5%
Contract liabilities - current		6,772		7,287		515		7.6%
Contract liabilities - long-term		11,073		11,290		217		2.0%

Schedule of leases

The following table shows the components of lease expenses for the three and nine months ended September 30, 2021 (in thousands):


	Three Months Ended September 30, 2021		Nine Months Ended September 30, 2021
Operating lease cost	$	2,292	$	7,040
Finance lease cost:
Amortization of right-of-use asset		471		1,743
Interest on lease liabilities		144		465
Total finance lease cost		615		2,208
Short-term lease cost		42		123
Variable lease cost		527		1,290
Total lease cost		3,476		10,661
Sublease income		—		(7)
Net lease cost	$	3,476	$	10,654

The following table shows the components of the lease assets and liabilities as of September 30, 2021 (in thousands):


	September 30, 2021
Operating leases:
Other long-term assets	$	30,411

Accrued liabilities	$	10,994
Deferred credits and other long-term liabilities		32,063
Total operating lease liabilities	$	43,057

Finance leases:
Property and equipment, net	$	9,637

Current debt, finance lease and deferred financing obligations	$	4,493
Long-term debt, finance lease and deferred financing obligations		8,524
Total finance lease liabilities	$	13,017

The following table shows the weighted average remaining lease term and discount rate as of September 30, 2021:


	September 30, 2021
Weighted average remaining lease term years
Operating leases		4.59
Finance leases		3.00
Weighted average discount rate
Operating leases		2.96%
Finance leases		4.41%

Supplemental cash flow information relating to leases is as follows (in thousands):


	Nine months ended September 30, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	10,483
Operating cash flows from finance leases		3,341
Financing cash flows from finance leases		465
Right-of-use asset obtained in exchange for new lease obligation
Operating leases		1,637
Finance leases		—

Schedule of fair value of financial assets and liabilities

In accordance with the fair value hierarchy described above, the following table shows the fair value of the Company’s assets that are required to be measured at fair value as of December 31, 2020 and September 30, 2021 (in thousands):


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents (1)	$	—	$	679,554	$	—	$	679,554
Investments:
U.S. Government and agency securities		42,399		—		—		42,399
Corporate debt securities		—		99,749		—		99,749
Certificates of deposit		—		1,311		—		1,311
Total assets held at fair value	$	42,399	$	780,614	$	—	$	823,013


	September 30, 2021
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents (2)	$	—	$	999,520	$	—	$	999,520
Investments:
U.S. Government and agency securities		16,530		—		—		16,530
Corporate debt securities		—		125,389		—		125,389
Taxable municipal bonds		—		12,299				12,299
Certificates of deposit		—		1,300		—		1,300
Total assets held at fair value	$	16,530	$	1,138,508	$	—	$	1,155,038

(1)	Excludes $464.9 million of cash held in bank accounts by the Company.

(2)	Excludes $38.9 million of cash held in bank accounts by the Company.

Summary of maturity dates of investments

The maturity dates of the Company’s investments as of September 30, 2021 are summarized below (in thousands):


	Amortized		Estimated
	Cost		Fair Value
2021	$	63,482	$	63,473
2022		92,097		92,045
Total investments at September 30, 2021	$	155,579	$	155,518

Schedule of nonvested restricted stock award

Summarized information related to the Company’s nonvested restricted stock awards (“RSAs”) for the nine months ended September 30, 2021 is as follows:


		Weighted
		Average
		Grant Date
	Shares	Fair Value
Outstanding, beginning of period	54,314	$	77.33
Awarded	6,312		94.56
Vested	—		—
Forfeited	—		—
Outstanding, ending of period	60,626		79.13

Schedule of nonvested restricted performance stock units

Summarized information related to the Company’s nonvested restricted performance stock units (“PSUs”) for the nine months ended September 30, 2021 is as follows:


		Weighted
		Average
		Grant Date
	Shares	Fair Value
Outstanding, beginning of period	278,945	$	99.80
Awarded	—		—
Vested	—		—
Forfeited	(63,324)		141.61
Outstanding, end of period	215,621		87.51