Marketable Securities (Tables)

12 Months Ended

Jan. 31, 2018

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 values of available-for-sale securities by major security type and class of security as of January 31, 2018 and 2017 are as follows:

	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Fair Value
As of January 31, 2018
Short-term Investments:
Corporate bonds	$	111,612	$	—	$	(184	)	$	111,428
Municipal and pre-refunded municipal bonds		52,474		11		(39	)		52,446
Certificates of deposit		1,251		—		—			1,251
		165,337		11		(223	)		165,125
Long-term Investments:
Corporate bonds		39,853		—		(228	)		39,625
Municipal and pre-refunded municipal bonds		9,873		8		(24	)		9,857
Mutual funds, held in rabbi trust		5,973		274		(10	)		6,237
Certificates of deposit		2,969		—		—			2,969
		58,668		282		(262	)		58,688
	$	224,005	$	293	$	(485	)	$	223,813
As of January 31, 2017
Short-term Investments:
Corporate bonds	$	59,403	$	7	$	(90	)	$	59,320
Municipal and pre-refunded municipal bonds		51,731		28		(12	)		51,747
		111,134		35		(102	)		111,067
Long-term Investments:
Corporate bonds		19,102		9		(33	)		19,078
Municipal and pre-refunded municipal bonds		19,488		35		(9	)		19,514
Mutual funds, held in rabbi trust		4,583		91		(1	)		4,673
Certificates of deposit		1,023		—		—			1,023
		44,196		135		(43	)		44,288
	$	155,330	$	170	$	(145	)	$	155,355

Gross Unrealized Losses and Fair Value of Marketable Securities

The following tables show the gross unrealized losses and fair value of the Company’s marketable securities with unrealized losses that are not deemed to be other-than-temporarily impaired aggregated by the length of time that individual securities have been in a continuous unrealized loss position, at January 31, 2018 and January 31, 2017, respectively.

	January 31, 2018
	Less Than 12 Months					12 Months or Greater				Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds	$	151,053	$	(412	)	$	—	$	—	$	151,053	$	(412	)
Municipal and pre-refunded municipal bonds		39,671		(63	)		—		—		39,671		(63	)
Mutual funds, held in rabbi trust		474		(10	)		—		—		474		(10	)
Total	$	191,198	$	(485	)	$	—	$	—	$	191,198	$	(485	)

	January 31, 2017
	Less Than 12 Months					12 Months or Greater				Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds	$	61,612	$	(123	)	$	—	$	—	$	61,612	$	(123	)
Municipal and pre-refunded municipal bonds		18,713		(21	)		—		—		18,713		(21	)
Mutual funds, held in rabbi trust		316		(1	)		—		—		316		(1	)
Total	$	80,641	$	(145	)	$	—	$	—	$	80,641	$	(145	)

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details