Restructuring Charges (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019	Nov. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 91,000	$ 801,000	$ 1,826,000	$ 3,993,000
Restructuring reserve	882,000		882,000		$ 2,203,000
Operating lease, impairment loss			1,200,000
2019 Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0		109,000
Restructuring reserve	165,000		165,000		1,460,000
2019 Restructuring Activities | Other Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	200,000		200,000
2017 Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			1,448,000
Restructuring reserve	659,000		659,000		$ 552,000
2017 Restructuring Activities | Other Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 700,000		$ 700,000