Fair Value of Financial Assets and Liabilities (Tables)

6 Months Ended

Oct. 31, 2012

Fair Value of Financial Assets and Liabilities [Abstract]

Summary of cash and cash equivalents

(in thousands)	October 31, 2012		April 30, 2012
Demand deposit accounts	$	41,427	$	45,361
Money market funds		3,689		288
U.S. Treasury bills		—		7,499
Corporate bonds (U.S. Gov. guaranteed)		—		21,219
Total cash and cash equivalents	$	45,116	$	74,367

Summary of short-term investments

(in thousands)	Cost		Gross Unrealized Losses			Fair Value
Available-for-sale securities:
Certificates of deposit (U.S. Gov. guaranteed)	$	10,226	$	(8	)	$	10,218
Corporate bonds		23,395		(9	)		23,386
U.S. Treasury notes		62,814		(10	)		62,804
Total short-term investments	$	96,435	$	(27	)	$	96,408

The following table summarizes the Company’s short-term investments as of April 30, 2012:

	Year Ended April 30, 2012
	Gross Unrealized
(in thousands)	Cost		Gains (Losses)			Fair Value
Available-for-sale securities:
Certificates of deposit (U.S. Gov. guaranteed)	$	4,510	$	(14	)	$	4,496
U.S. Treasury notes		28,126		(28	)		28,099
Corporate bonds		18,245		(5	)		18,239
Total short-term investments	$	50,881	$	(47	)	$	50,834

Summary of fair value of financial assets and liabilities

	Fair Value Measurements at October 31, 2012								Fair Value Measurements at April 30, 2012
(in thousands)	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	3,689	$	—	$	—	$	3,689	$	288	$	—	$	—	$	288
U.S. Treasury bills		—		—		—		—		7,499		—		—		7,499
Corporate bonds (U.S. Gov. guaranteed)		—		—		—		—		21,219		—		—		21,219
Total cash equivalents		3,689		—		—		3,689		29,006		—		—		29,006
Restricted cash		604		—		—		604		500		—		—		500
Short-term investments:
Certificates of deposit (U.S. Gov. guaranteed)		10,218		—		—		10,218		4,496		—		—		4,496
Corporate bonds		23,386		—		—		23,386		18,239		—		—		18,239
U.S. Treasury notes		62,804		—		—		62,804		28,099		—		—		28,099
Total short-term investments		96,408		—		—		96,408		50,834		—		—		50,834
Total assets	$	100,701	$	—	$	—	$	100,701	$	80,340	$	—	$	—	$	80,340