Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	$ 121,741	$ 116,833
Cash, Cash Equivalents and Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	248,861	244,728
Unrealized Gains	10	22
Unrealized Losses	0	0
Aggregate Fair Value	248,871	244,750
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	127,130	127,917
Unrealized Gains	0	0
Unrealized Losses	0	0
Aggregate Fair Value	127,130	127,917
Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	121,731	116,811
Unrealized Gains	10	22
Unrealized Losses	0	0
Aggregate Fair Value	121,741	116,833
Money market funds \| Cash, Cash Equivalents and Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	113,131	92,272
Unrealized Gains	0	0
Unrealized Losses	0	0
Aggregate Fair Value	113,131	92,272
U.S. government and agency securities \| Cash, Cash Equivalents and Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	109,977	115,412
Unrealized Gains	10	13
Unrealized Losses	0	0
Aggregate Fair Value	109,987	115,425
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	16,754	13,713
Commercial paper \| Cash, Cash Equivalents and Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,753	31,379
Unrealized Gains	0	0
Unrealized Losses	0	0
Aggregate Fair Value	$ 25,753	31,379
Corporate notes and bonds \| Cash, Cash Equivalents and Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		5,665
Unrealized Gains		9
Unrealized Losses		0
Aggregate Fair Value		$ 5,674

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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