Investments (Tables)

12 Months Ended

Apr. 30, 2016

Investments

Schedule of investments

	April 30,
	2016		2015
	(In thousands)
Short-term investments:
Held-to-maturity securities:
Municipal securities	$	42,179	$	67,173
U.S. government securities		21,184		11,536
Corporate bonds		40,041		1,314
Certificates of deposit		—		3,885
Total held-to-maturity investments	$	103,404	$	83,908
Available for sale securities:
Equity securities		—		1,473
Total available for sale investments		—		1,473
Total short-term investments	$	103,404	$	85,381
Long-term investments:
Held-to-maturity securities:
Municipal securities	$	—	$	30,418
U.S. government securities		7,518		5,009
Corporate bonds		23,561		8,501
Certificates of deposit		—		—
Total held-to-maturity investments		31,079		43,928
Available-for-sale securities:
Auction rate securities		2,780		2,841
Convertible bonds		—		—
Equity securities		—		—
Total available-for-sale investments		2,780		2,841
Total long-term investments	$	33,859	$	46,769

Equity securities

Investments

Schedule of amortized cost and fair value by contractual maturity

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

	April 30,
	2016		2015
Equity Securities
Amortized cost	$	—	$	3,357
Gross unrealized gains		—		—
Gross unrealized losses		—		(1,884)
Fair value	$	—	$	1,473

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):

	2016								2015
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
Municipal securities	$	42,179	$	5	$	(7)	$	42,177	$	97,591	$	8	$	(35)	$	97,564
U.S. government securities		28,702		23		—		28,725		16,545		12		—		16,557
Corporate bonds		63,602		54		(32)		63,624		9,815		—		(13)		9,802
Certificates of deposit		—		—		—		—		3,885		—		—		3,885
Total held to maturity investments	$	134,483	$	82	$	(39)	$	134,526	$	127,836	$	20	$	(48)	$	127,808

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, 2016, are as follows:

	Cost		Fair Value
Due within one year	$	103,404	$	103,415
Due after one year through five years		31,079		31,111
Total	$	134,483	$	134,526

Available-for-sale securities | Auction rate securities

Investments

Schedule of amortized cost and fair value by contractual maturity

The amortized cost and fair value of the Company’s auction rate securities by contractual maturity at April 30, 2016 are as follows (in thousands):

	Cost		Fair Value
Due after one through five years	$	1,100	$	1,060
Due after 10 years		2,000		1,720
Total	$	3,100	$	2,780

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,
	2016		2015
Auction rate securities
Amortized cost	$	3,100	$	3,200
Gross unrealized losses		(320)		(359)
Fair value	$	2,780	$	2,841