Cash, Cash Equivalents and Investments (Summary Of Cash, Cash Equivalents And Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Aug. 31, 2020	Nov. 30, 2019
Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	$ 220,575	$ 154,259
Unrealized Gains	131	23
Unrealized Losses	0	0
Total Amortized Cost Basis	229,988	173,662
Total Fair Value	230,119	173,685
State and municipal bond obligations
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis		7,036
Unrealized Gains		1
Unrealized Losses		0
Fair Value		7,037
U.S. treasury bonds
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	4,994	7,221
Unrealized Gains	75	10
Unrealized Losses	0	0
Fair Value	5,069	7,231
Corporate bonds
Cash, Cash Equivalents and Investments [Line Items]
Amortized Cost Basis	4,419	5,146
Unrealized Gains	56	12
Unrealized Losses	0	0
Fair Value	4,475	5,158
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	214,037	144,346
Money market funds
Cash, Cash Equivalents and Investments [Line Items]
Cash and cash equivalents	$ 6,538	$ 9,913