Investments (Tables)

12 Months Ended

Apr. 30, 2017

Investments

Schedule of investments

	April 30,
	2017		2016
	(In thousands)
Short-term investments:
Held-to-maturity securities:
Municipal securities	$	47,437	$	42,179
U.S. government securities		14,515		21,184
Corporate bonds		55,519		40,041
Certificates of deposit		2,500		—
Total held-to-maturity and short-term investments	$	119,971	$	103,404
Long-term investments:
Held-to-maturity securities:
Municipal securities	$	8,942	$	—
U.S. government securities		22,540		7,518
Corporate bonds		8,117		23,561
Total held-to-maturity investments		39,599		31,079
Available-for-sale securities:
Auction rate securities		2,497		2,780
Total available-for-sale investments		2,497		2,780
Total long-term investments	$	42,096	$	33,859

Held-to-maturity securities

Investments

Schedule of amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of held-to-maturity investments

The amortized cost, gross unrealized losses, and estimated fair value of the held‑to‑maturity investments as of April 30, are as follows (in thousands):

	April 30, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Municipal securities	$	56,379	$	30	$	(21)	$	56,388
U.S. government securities		37,055		2		(41)		37,016
Corporate bonds		63,636		9		(85)		63,560
Certificates of deposit		2,500		1		—		2,501
Total held-to-maturity investments	$	159,570	$	42	$	(147)	$	159,465

Schedule of amortized cost and fair value by contractual maturity

The amortized cost and fair value of the Company’s held‑to‑maturity securities by contractual maturity at April 30, 2017, are as follows:

	Cost		Fair Value
Due within one year	$	119,971	$	119,893
Due after one year through five years		39,599		39,572
Total	$	159,570	$	159,465

Available-for-sale securities | Auction rate securities

Investments

Schedule of amortized cost and fair value by contractual maturity

	April 30,
	2017		2016
Auction rate securities
Amortized cost	$	2,700	$	3,100
Gross unrealized losses		(203)		(320)
Fair value	$	2,497	$	2,780

The amortized cost and fair value of the Company’s auction rate securities by contractual maturity at April 30, 2017 are as follows (in thousands):

	Cost		Fair Value
Due after one through five years	$	700	$	701
Due after 10 years		2,000		1,796
Total	$	2,700	$	2,497

Schedule of amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of available-for-sale investments

The amortized cost, gross unrealized losses, and estimated fair value of the available‑for‑sale auction rate securities are as follows (in thousands):

	April 30,
	2017		2016
Auction rate securities
Amortized cost	$	2,700	$	3,100
Gross unrealized losses		(203)		(320)
Fair value	$	2,497	$	2,780