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Marketable Securities (Tables)
 9 Months Ended
Oct. 31, 2021
Investments Debt And Equity Securities [Abstract]  
Amortized Cost, Gross Unrealized Gains (Losses) and Fair Value of Available-For-Sale Securities The amortized cost, gross unrealized gains (losses) and fair value of available-for-sale securities by major security type and class of security as of October 31, 2021, January 31, 2021 and October 31, 2020 were as follows:

 

 

 

Amortized

 

 

Unrealized

 

 

Unrealized

 

 

Fair

 

 

 

Cost

 

 

Gains

 

 

(Losses)

 

 

Value

 

As of October 31, 2021

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Short-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corporate bonds

 

$

53,744

 

 

$

3

 

 

$

(71

)

 

$

53,676

 

Municipal and pre-refunded municipal bonds

 

 

114,818

 

 

 

9

 

 

 

(73

)

 

 

114,754

 

Treasury bills

 

 

16,849

 

 

 

—

 

 

 

(3

)

 

 

16,846

 

Commercial paper

 

 

3,099

 

 

 

—

 

 

 

—

 

 

 

3,099

 

 

 

 

188,510

 

 

 

12

 

 

 

(147

)

 

 

188,375

 

Long-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corporate bonds

 

 

174,884

 

 

 

1

 

 

 

(1,125

)

 

$

173,760

 

Municipal and pre-refunded municipal bonds

 

 

78,955

 

 

 

8

 

 

 

(362

)

 

 

78,601

 

Treasury bills

 

 

4,748

 

 

 

—

 

 

 

(7

)

 

 

4,741

 

Mutual funds, held in rabbi trust

 

 

11,540

 

 

 

542

 

 

 

(1

)

 

 

12,081

 

Federal government agencies

 

 

350

 

 

 

—

 

 

 

(2

)

 

 

348

 

Certificates of deposit

 

 

249

 

 

 

—

 

 

 

—

 

 

 

249

 

 

 

 

270,726

 

 

 

551

 

 

 

(1,497

)

 

 

269,780

 

 

 

$

459,236

 

 

$

563

 

 

$

(1,644

)

 

$

458,155

 

As of January 31, 2021

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Short-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corporate bonds

 

$

38,695

 

 

$

1

 

 

$

(48

)

 

$

38,648

 

Municipal and pre-refunded municipal bonds

 

 

127,097

 

 

 

11

 

 

 

(53

)

 

 

127,055

 

Commercial paper

 

 

8,992

 

 

 

—

 

 

 

—

 

 

 

8,992

 

 

 

 

174,784

 

 

 

12

 

 

 

(101

)

 

 

174,695

 

Long-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corporate bonds

 

 

59,890

 

 

 

3

 

 

 

(129

)

 

 

59,764

 

Municipal and pre-refunded municipal bonds

 

 

53,134

 

 

 

17

 

 

 

(46

)

 

 

53,105

 

Mutual funds, held in rabbi trust

 

 

10,827

 

 

 

20

 

 

 

(54

)

 

 

10,793

 

 

 

 

123,851

 

 

 

40

 

 

 

(229

)

 

 

123,662

 

 

 

$

298,635

 

 

$

52

 

 

$

(330

)

 

$

298,357

 

As of October 31, 2020

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Short-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corporate bonds

 

$

2

 

 

$

—

 

 

$

—

 

 

$

2

 

 

 

 

2

 

 

 

—

 

 

 

—

 

 

 

2

 

Long-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Corporate bonds

 

 

30

 

 

 

—

 

 

 

—

 

 

 

30

 

Municipal and pre-refunded municipal bonds

 

 

53

 

 

 

1

 

 

 

—

 

 

 

54

 

Mutual funds, held in rabbi trust

 

 

9,393

 

 

 

17

 

 

 

(144

)

 

 

9,266

 

 

 

 

9,476

 

 

 

18

 

 

 

(144

)

 

 

9,350

 

 

 

$

9,478

 

 

$

18

 

 

$

(144

)

 

$

9,352