Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from External Customer [Line Items]
Changes in contract estimates related to projects in progress	$ 5.5	$ 4.3
Transferred over Time | Product Concentration Risk | Revenue from Contract with Customer Benchmark
Revenue from External Customer [Line Items]
Concentration risk, percentage	92.00%	95.00%
Transferred at Point in Time | Product Concentration Risk | Revenue from Contract with Customer Benchmark
Revenue from External Customer [Line Items]
Concentration risk, percentage	8.00%	5.00%