Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Financial Instruments Disclosure [Abstract]

Summary of Estimated Fair Value and Related Valuation Input Hierarchy of Available-for-Sale Securities

The following tables summarize the estimated fair value and related valuation input hierarchy of our available-for-sale securities as of each period end:

		Total			Total		Total			Total
		Amortized			Unrealized		Unrealized			Estimated
As of December 31, 2021:	Input Level	Cost			Gain		Loss			Fair Value
		(in thousands)
Money market funds	Level 1	$	89,738		$	—	$	—		$	89,738
U.S. Treasury obligations	Level 2		111,832			1		(138	)	$	111,695
Government agency obligations	Level 2		21,346			—		(23	)	$	21,323
Corporate debt obligations	Level 2		99,757			6		(190	)	$	99,573
Commercial paper	Level 2		36,993			—		—		$	36,993
Asset-backed securities	Level 2		10,174			1		(25	)	$	10,150
Total available-for-sale securities			369,840			8		(376	)		369,472
Less: amounts classified as cash equivalents			(104,488	)						$	(104,488	)
Amounts classified as short-term investments		$	265,352		$	8	$	(376	)	$	264,984
		Total			Total		Total			Total
		Amortized			Unrealized		Unrealized			Estimated
As of December 31, 2020:	Input Level	Cost			Gain		Loss			Fair Value
		(in thousands)
Money market funds	Level 1	$	168,343		$	—	$	—		$	168,343
U.S. Treasury obligations	Level 2		230,239			113		(6	)		230,346
Government agency obligations	Level 2		22,537			22		(3	)		22,556
Corporate debt obligations	Level 2		50,080			166		(1	)		50,245
Commercial paper	Level 2		17,990			—		—			17,990
Asset-backed securities	Level 2		9,860			10		(5	)		9,865
Total available-for-sale securities			499,049			311		(15	)		499,345
Less: amounts classified as cash equivalents			(199,090	)		—		—			(199,090	)
Amounts classified as short-term investments		$	299,959		$	311	$	(15	)	$	300,255

Amortized Cost and Fair Value of Available for Sale Securities by Contractual Maturity

The amortized cost and fair value of our available-for-sale securities by contractual maturity were as follows:

	As of December 31, 2021				As of December 31, 2020
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
	(in thousands)				(in thousands)
Maturing within one year	$	278,457	$	278,354	$	434,828	$	435,023
Maturing in one to five years		91,383		91,118		64,221		64,322
Total available-for-sale securities	$	369,840	$	369,472	$	499,049	$	499,345

Reconciliation of Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash within the consolidated balance sheets that sum to the total of the same such amounts in the consolidated statement of cash flows:

	December 31,		December 31,
	2021		2020
	(in thousands)
Cash and cash equivalents	$	106,084	$	200,404
Restricted cash - short-term		194		194
Restricted cash - long-term		1,200		1,200
Total cash, cash equivalents and restricted cash	$	107,478	$	201,798