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Marketable Securities (Tables)
 3 Months Ended
Apr. 30, 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 April 30, 2021, January 31, 2021 and April 30, 2020 were as follows:

 

 

 

Amortized

 

 

Unrealized

 

 

Unrealized

 

 

Fair

 

 

 

Cost

 

 

Gains

 

 

(Losses)

 

 

Value

 

As of April 30, 2021

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Short-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Municipal and pre-refunded municipal bonds

 

$

106,266

 

 

$

5

 

 

$

(84

)

 

$

106,187

 

Corporate bonds

 

 

48,500

 

 

 

1

 

 

 

(49

)

 

 

48,452

 

Commercial paper

 

 

9,791

 

 

 

—

 

 

 

—

 

 

 

9,791

 

 

 

 

164,557

 

 

 

6

 

 

 

(133

)

 

 

164,430

 

Long-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Municipal and pre-refunded municipal bonds

 

 

40,085

 

 

 

17

 

 

 

(48

)

 

$

40,054

 

Corporate bonds

 

 

48,850

 

 

 

2

 

 

 

(111

)

 

 

48,741

 

Mutual funds, held in rabbi trust

 

 

11,448

 

 

 

437

 

 

 

—

 

 

 

11,885

 

 

 

 

100,383

 

 

 

456

 

 

 

(159

)

 

 

100,680

 

 

 

$

264,940

 

 

$

462

 

 

$

(292

)

 

$

265,110

 

As of January 31, 2021

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Short-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Municipal and pre-refunded municipal bonds

 

$

127,097

 

 

$

11

 

 

$

(53

)

 

$

127,055

 

Corporate bonds

 

 

38,695

 

 

 

1

 

 

 

(48

)

 

 

38,648

 

Commercial paper

 

 

8,992

 

 

 

—

 

 

 

—

 

 

 

8,992

 

 

 

 

174,784

 

 

 

12

 

 

 

(101

)

 

 

174,695

 

Long-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Municipal and pre-refunded municipal bonds

 

 

53,134

 

 

 

17

 

 

 

(46

)

 

 

53,105

 

Corporate bonds

 

 

59,890

 

 

 

3

 

 

 

(129

)

 

 

59,764

 

Mutual funds, held in rabbi trust

 

 

10,827

 

 

 

20

 

 

 

(54

)

 

 

10,793

 

 

 

 

123,851

 

 

 

40

 

 

 

(229

)

 

 

123,662

 

 

 

$

298,635

 

 

$

52

 

 

$

(330

)

 

$

298,357

 

 

 

Amortized

 

 

Unrealized

 

 

Unrealized

 

 

Fair

 

 

 

Cost

 

 

Gains

 

 

(Losses)

 

 

Value

 

As of April 30, 2020

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Short-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Municipal and pre-refunded municipal bonds

 

$

50,887

 

 

$

5

 

 

$

(31

)

 

$

50,861

 

Corporate bonds

 

 

14,246

 

 

 

21

 

 

 

(7

)

 

 

14,260

 

 

 

 

65,133

 

 

 

26

 

 

 

(38

)

 

 

65,121

 

Long-term Investments:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Municipal and pre-refunded municipal bonds

 

 

2,350

 

 

 

21

 

 

 

(1

)

 

 

2,370

 

Corporate bonds

 

 

2,572

 

 

 

3

 

 

 

(4

)

 

 

2,571

 

Mutual funds, held in rabbi trust

 

 

7,400

 

 

 

682

 

 

 

—

 

 

 

8,082

 

Certificates of deposit

 

 

249

 

 

 

—

 

 

 

—

 

 

 

249

 

 

 

 

12,571

 

 

 

706

 

 

 

(5

)

 

 

13,272

 

 

 

$

77,704

 

 

$

732

 

 

$

(43

)

 

$

78,393