Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Trading And Available-For-Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2015	Nov. 30, 2014
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	$ 211,080	$ 283,182
Unrealized Gains	84	86
Unrealized Losses	0	0
Fair Value	211,164	283,268
State and municipal bond obligations [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	24,045	20,100
Unrealized Gains	84	86
Unrealized Losses	0	0
Fair Value	24,129	20,186
Cash [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	144,157	195,189
Fair Value	144,157	195,189
Money market funds [Member]
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	42,878	67,893
Fair Value	$ 42,878	$ 67,893