Business Combinations (Narrative) (Details) business in Thousands			3 Months Ended			9 Months Ended
	May 31, 2020 USD ($)	Apr. 30, 2019 USD ($) business	Aug. 31, 2020 USD ($)	May 31, 2020 USD ($)	Aug. 31, 2019 USD ($)	Aug. 31, 2020 USD ($)	Aug. 31, 2019 USD ($)	Nov. 30, 2019 USD ($)
Business Acquisition [Line Items]
Increase (decrease) in measurement period adjustments						$ (838,000)
Goodwill			$ 431,864,000			431,864,000		$ 432,824,000
Stock-based compensation expense			5,685,000		$ 5,490,000	17,359,000	$ 17,411,000
Acquisition-related expenses			1,125,000		253,000	1,439,000	1,360,000
Acquired intangible assets			111,300,000			$ 111,300,000
Effective income tax rate						24.50%
Ipswitch
Business Acquisition [Line Items]
Total purchase consideration		$ 225,000,000.0
Escrow deposit		$ 22,500,000
Number of small and medium-sized businesses | business		24
Increase (decrease) in measurement period adjustments	$ (618,000)			$ (600,000)
Goodwill	117,033,000	$ 117,000,000.0		117,033,000
Ipswitch | Restricted Stock Units
Business Acquisition [Line Items]
Equity interest issued		$ 2,000,000.0
Period of non-compete agreement		3 years
Intangible assets amortization period		3 years
Stock-based compensation expense						$ 500,000
Acquisition-related expenses			100,000			400,000
Revenue of acquisition			$ 17,600,000		$ 10,700,000	$ 50,100,000	$ 14,000,000.0
Term Loan | Ipswitch
Business Acquisition [Line Items]
Term loan		$ 185,000,000.0
Term loan and maximum borrowing capacity		401,000,000.0
Customer-related | Ipswitch
Business Acquisition [Line Items]
Finite-lived intangible assets	66,600,000	66,600,000		66,600,000
Purchased technology | Ipswitch
Business Acquisition [Line Items]
Finite-lived intangible assets	33,100,000	33,100,000		33,100,000
Trade name | Ipswitch
Business Acquisition [Line Items]
Finite-lived intangible assets	$ 9,600,000	$ 9,600,000		$ 9,600,000