Marketable Securities

12 Months Ended

Jan. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

As of January 31, 2021 and 2020, our marketable securities consisted of the following: 

	As of January 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(in thousands)
Commercial paper	$	26,222	$	—	$	—	$	26,222
Agency bonds	461,335		79		(49)		461,365
Corporate and other debt securities	465,207		1,113		(64)		466,256
U.S. government agency securities	834,894		28		(257)		834,665
Treasury bills	215,902		6		(6)		215,902
Marketable securities	$	2,003,560	$	1,226	$	(376)	$	2,004,410

	As of January 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(in thousands)
Commercial paper	$	37,894	$	—	$	—	$	37,894
Agency bonds	141,157		49		(43)		141,163
Corporate and other debt securities	320,407		775		(16)		321,166
U.S. government agency securities	71,794		45		(2)		71,837
Marketable securities	$	571,252	$	869	$	(61)	$	572,060

We review the individual securities that have unrealized losses on a regular basis to evaluate whether or not any security has experienced, or is expected to experience, credit losses resulting in the decline in fair value. We evaluate, among other factors, whether we have the intention to sell any of these marketable securities and whether it is more likely than not that we will be required to sell any of them before recovery of the amortized cost basis. We have not recorded an allowance for credit losses, as we believe any such losses would be immaterial based on the high-grade credit rating for each of our marketable securities as of the end of each fiscal year. There were no material realized gains or losses from available-for-sale securities that were reclassified out of accumulated other comprehensive income for the fiscal years ended January 31, 2021, 2020, and 2019.

The following table presents the contractual maturities of our marketable securities as of January 31, 2021 and 2020:

	As of January 31,
	2021		2020
	(in thousands)
Less than one year	$	1,017,048	$	315,900
Due in one to five years	987,362		256,160
Total	$	2,004,410	$	572,060