Commitments and Contingencies - Summary of Environmental Reserve Activity (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 296.4
Additions/Adjustments	23.6
Expenditures	(26.6)
Ending balance	293.4
Aerojet Rocketdyne- Sacramento
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	214.7
Additions/Adjustments	23.0
Expenditures	(16.2)
Ending balance	221.5
Aerojet Rocketdyne- BPOU
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	64.7
Additions/Adjustments	0.7
Expenditures	(9.1)
Ending balance	56.3
Other Aerojet Rocketdyne Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	11.8
Additions/Adjustments	(0.2)
Expenditures	(1.1)
Ending balance	10.5
Total Aerojet Rocketdyne
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	291.2
Additions/Adjustments	23.5
Expenditures	(26.4)
Ending balance	288.3
Other
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5.2
Additions/Adjustments	0.1
Expenditures	(0.2)
Ending balance	$ 5.1