Fair Value Measurements (Tables)

12 Months Ended

May 31, 2013

Fair Value Disclosures [Abstract]

Schedule of fair value of financial instruments measured on a recurring basis

These financial instruments measured at fair value on a recurring basis are summarized below:

(In thousands)	As of May 31, 2013
	Level 1		Level 2		Level 3		Fair Value
Cash and cash equivalents	$	352,273	$	—	$	—	$	352,273
Marketable securities:
U.S. municipal bonds	—		5,680		—		5,680
Accounts receivable, net	—		39		—		39
Total assets at fair value	$	352,273	$	5,719	$	—	$	357,992

(In thousands)	As of May 31, 2012
	Level 1		Level 2		Level 3		Fair Value
Cash and cash equivalents	$	339,825	$	—	$	—	$	339,825
Total assets at fair value	$	339,825	$	—	$	—	$	339,825