Revenue Recognition Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Oct. 01, 2019	Sep. 30, 2019
Revenue Recognition [Abstract]
Contract with Customer, Asset, after Allowance for Credit Loss, Current	$ 39,800		$ 39,800			$ 58,700
Deferred Costs, Current	18,600		18,600			17,200
Contract with Customer, Liability	367,038		367,038		$ 348,006
Capitalized Contract Cost, Net	18,900		18,900			19,900
Hardware revenue	5,700	$ 6,400	20,500	$ 21,500
Capitalized Contract Cost, Net, Noncurrent	44,100		44,100			30,100
Capitalized Contract Cost, Amortization	4,700	$ 4,300	13,300	$ 11,300
Deferred Costs, Noncurrent	32,700		32,700			38,500
Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent	$ 124,700		$ 124,700			$ 108,700