Fair Value of Assets and Liabilities Acquired (Detail) - USD ($) $ in Thousands		May 31, 2017		Feb. 28, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money markets		$ 326,350	[1]	$ 258,188	[2]
Interest-bearing deposits	[1]	27,942
Available-for-sale securities		1,405,474		1,300,611
Foreign currency derivatives, assets		278	[3]	135	[4]
Foreign currency derivatives, liabilities		(137)	[5]	(160)	[6]
Total		1,405,615		1,300,586
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	[1]	20,926
U.S. Agencies Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		332,764	[1]	327,430	[2]
Corporate Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		697,492	[1]	714,993	[2]
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money markets		326,350	[1]	258,188	[2]
Total		326,350		258,188
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest-bearing deposits	[1]	27,942
Foreign currency derivatives, assets		278	[3]	135	[4]
Foreign currency derivatives, liabilities		(137)	[5]	(160)	[6]
Total		1,079,265		1,042,398
Fair Value, Inputs, Level 2 | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	[1]	20,926
Fair Value, Inputs, Level 2 | U.S. Agencies Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		332,764	[1]	327,430	[2]
Fair Value, Inputs, Level 2 | Corporate Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities		$ 697,492	[1]	$ 714,993	[2]

[1] Included in Cash and cash equivalents, Investments in debt securities, short-term or Investments in debt securities, long-term in the Company's Consolidated Balance Sheet as of May 31, 2017, in addition to $904.1 million of cash.

[2] Included in Cash and cash equivalents, Investments in debt securities, short-term or Investments in debt securities, long-term in the Company's Consolidated Balance Sheet as of February 28, 2017, in addition to $832.6 million of cash.

[3] Included in Other current assets in the Company's Consolidated Balance Sheet as of May 31, 2017.

[4] Included in Other current assets in the Company's Consolidated Balance Sheet as of February 28, 2017.

[5] Included in Accounts payable and accrued expenses in the Company's Consolidated Balance Sheet as of May 31, 2017.

[6] Included in Accounts payable and accrued expenses in the Company's Consolidated Balance Sheet as of February 28, 2017.