Fair Value Measurements (Schedule Of Items Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Nov. 30, 2017	Feb. 28, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market securities	$ 302,456	$ 397,994
Mutual fund investments	19,311	16,519
Derivative instruments	6,904	2,997
Total assets at fair value	$ 328,671	$ 417,510
Percent of total assets at fair value	100.00%	100.00%
Percent of total assets	1.90%	2.60%
Liabilities: Derivative instruments	$ 0	$ (509)
Total liabilities at fair value	$ 0	$ (509)
Percent of total liabilities	0.00%	0.00%
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market securities	$ 302,456	$ 397,994
Mutual fund investments	19,311	16,519
Derivative instruments	0	0
Total assets at fair value	$ 321,767	$ 414,513
Percent of total assets at fair value	97.90%	99.30%
Percent of total assets	1.90%	2.50%
Liabilities: Derivative instruments	$ 0	$ 0
Total liabilities at fair value	$ 0	$ 0
Percent of total liabilities	0.00%	0.00%
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market securities	$ 0	$ 0
Mutual fund investments	0	0
Derivative instruments	6,904	2,997
Total assets at fair value	$ 6,904	$ 2,997
Percent of total assets at fair value	2.10%	0.70%
Percent of total assets	0.00%	0.00%
Liabilities: Derivative instruments	$ 0	$ (509)
Total liabilities at fair value	$ 0	$ (509)
Percent of total liabilities	0.00%	0.00%