Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Revenue from External Customer [Line Items]
Changes in contract estimates related to projects in progress			$ 8.2	$ 9.0
Transferred over Time | Product Concentration Risk | Revenue from Contract with Customer Benchmark
Revenue from External Customer [Line Items]
Concentration risk, percentage	93.00%	96.00%	92.00%	96.00%
Transferred at Point in Time | Product Concentration Risk | Revenue from Contract with Customer Benchmark
Revenue from External Customer [Line Items]
Concentration risk, percentage	7.00%	4.00%	8.00%	4.00%