Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales to external customers	$ 383,861	$ 347,827	$ 351,663	$ 346,105	$ 412,468	$ 360,343	$ 348,628	$ 323,002	$ 1,429,456	$ 1,444,441	$ 1,339,541
Transferred over Time [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales to external customers									$ 592,755	$ 563,386
Minimum [Member] | Transferred at Point in Time [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales to external customers	$ 100