Fair Value Disclosures (Tables)

12 Months Ended

May. 31, 2015

Fair Value Disclosures [Abstract]

Summary of Financial Instruments Measured at Fair Value on a Recurring Basis

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

	As of May 31, 2015
(In thousands)	Level 1		Level 2		Level 3		Fair Value
Cash and cash equivalents	$	417,073	$	—	$	—	$	417,073
Marketable securities:
Canadian treasury securities	—		16,081		—		16,081
Total assets at fair value	$	417,073	$	16,081	$	—	$	433,154

	As of May 31, 2014
(In thousands)	Level 1		Level 2		Level 3		Fair Value
Cash and cash equivalents	$	513,288	$	—	$	—	$	513,288
Total assets at fair value	$	513,288	$	—	$	—	$	513,288
Current accrued liabilities	$	—	$	286	$	—	$	286
Total liabilities at fair value	$	—	$	286	$	—	$	286