Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash

12 Months Ended

Dec. 31, 2020

Notes to Financial Statements

Financial Instruments Disclosure [Text Block]

3.  CASH, CASH EQUIVALENTS, INVESTMENTS AND RESTRICTED CASH

The following is a summary of the Company’s cash, cash equivalents and debt investments (in thousands): 

	December 31,
	2020		2019
Cash	$	300,609	$	144,860
Money market funds		34,335		28,100
Corporate debt securities		249,671		260,950
Commercial paper		2,999		1,994
U.S. treasuries and government agency bonds		7,499		19,493
Auction-rate securities backed by student-loan notes		2,861		3,138
Total	$	597,974	$	458,535

	December 31,
	2020		2019
Reported as:
Cash and cash equivalents	$	334,944	$	172,960
Short-term investments		260,169		282,437
Investment within other long-term assets		2,861		3,138
Total	$	597,974	$	458,535

The following table summarizes the contractual maturities of the short-term and long-term available-for-sale investments as of December 31, 2020 (in thousands): 

	Amortized Cost		Fair Value
Due in less than 1 year	$	97,773	$	98,036
Due in 1 - 5 years		160,316		162,133
Due in greater than 5 years		3,020		2,861
Total	$	261,109	$	263,030

For the year ended December 31, 2020, the Company recognized gross realized gains of $1.1 million on the sale of investments. Gross realized gains were not material for the years ended December 31, 2019 and 2018. Gross realized losses were not material for any period presented.

The following tables summarize the unrealized gain and loss positions related to the available-for sale investments (in thousands): 

	December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	34,335	$	-	$	-		$	34,335
Corporate debt securities		247,591		2,177		(97	)		249,671
Commercial paper		2,999		-		-			2,999
U.S. treasuries and government agency bonds		7,499		2		(2	)		7,499
Auction-rate securities backed by student-loan notes		3,020		-		(159	)		2,861
Total	$	295,444	$	2,179	$	(258	)	$	297,365

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	28,100	$	-	$	-		$	28,100
Corporate debt securities		260,645		383		(78	)		260,950
Commercial paper		1,994		-		-			1,994
U.S. treasuries and government agency bonds		19,487		7		(1	)		19,493
Auction-rate securities backed by student-loan notes		3,320		-		(182	)		3,138
Total	$	313,546	$	390	$	(261	)	$	313,675

The following tables present information about the available-for-sale investments that had been in a continuous unrealized loss position for less than 12 months and for greater than 12 months (in thousands):

	December 31, 2020
	Less than 12 Months					Greater than 12 Months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	59,144	$	(97	)	$	-	$	-		$	59,144	$	(97	)
U.S. treasuries and government agency bonds		5,998		(2	)		-		-			5,998		(2	)
Auction-rate securities backed by student-loan notes		-		-			2,861		(159	)		2,861		(159	)
Total	$	65,142	$	(99	)	$	2,861	$	(159	)	$	68,003	$	(258	)

	December 31, 2019
	Less than 12 Months					Greater than 12 Months					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate debt securities	$	82,126	$	(63	)	$	11,136	$	(15	)	$	93,262	$	(78	)
U.S. treasuries and government agency bonds		993		(1	)		-		-			993		(1	)
Auction-rate securities backed by student-loan notes		-		-			3,138		(182	)		3,138		(182	)
Total	$	83,119	$	(64	)	$	14,274	$	(197	)	$	97,393	$	(261	)

An impairment exists when the fair value of an investment is less than its amortized cost basis. As of  December 31, 2020, the Company did not consider the impairment of its investments to be a result of credit losses. As of  December 31, 2019, the Company did not consider the impairment of its investments to be other-than-temporary. The Company typically invests in highly rated securities, with the primary objective of minimizing the potential risk of principal loss. The Company’s investment policy generally requires securities to be investment grade and limits the amount of credit exposure to any one issuer. When evaluating a debt security for impairment, management reviews factors such as the Company’s intent to sell, or whether it will more likely than not be required to sell, the security before recovery of its amortized cost basis, the extent to which the fair value of the security is less than its cost, the financial condition of the issuer and the credit quality of the investment.

The Company’s auction-rate securities are backed by pools of student loans supported by guarantees by the U.S. Department of Education. The underlying maturities of these securities are up to 25 years.  The Company has received all scheduled interest payments on a timely basis pursuant to the terms and conditions of the securities. The Company does not intend to sell these securities, and it is more likely than not that the Company will not be required to sell these securities, before recovery of its amortized cost basis. To date, the Company has redeemed $40.3 million, or 93% of the original portfolio in these auction-rate securities, at par without any realized losses.

Non-Marketable Equity Investment

In November 2020, the Company made an equity investment in a privately held company (the “Investee”) that is accounted for under the measurement alternative. One member of the Company’s Board of Directors is an executive officer of a company that has a commercial relationship with the Investee. In addition, the Company’s Chief Executive Officer has a personal investment in the Investee. As of December 31, 2020, the Company’s investment had a carrying value of $3.4 million. The Company did not record any impairment or adjustments resulting from observable price changes for the year ended December 31, 2020.

Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported on the Consolidated Balance Sheets to the amounts reported on the Consolidated Statements of Cash Flows (in thousands):   

	December 31,
	2020		2019
Cash and cash equivalents	$	334,944	$	172,960
Restricted cash included in other long-term assets		127		116
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$	335,071	$	173,076

As of  December 31, 2020 and 2019, restricted cash included a security deposit that is set aside in a bank account and cannot be withdrawn by the Company under the terms of a lease agreement. The restriction will end upon the expiration of the lease.