Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Summary of Environmental Reserve Activity

The following table summarizes the Company’s environmental reserve activity:

	Aerojet Rocketdyne- Sacramento		Aerojet Rocketdyne- BPOU		Other Aerojet Rocketdyne Sites		Total Aerojet Rocketdyne		Other		Total Environmental Reserve
	(In millions)
December 31, 2017	$	206.5	$	116.4	$	13.7	$	336.6	$	4.8	$	341.4
Additions	20.1		2.3		0.6		23.0		0.3		23.3
Expenditures	(19.2)		(14.9)		(1.9)		(36.0)		(0.8)		(36.8)
December 31, 2018	207.4		103.8		12.4		323.6		4.3		327.9
Additions	17.0		(0.8)		0.3		16.5		0.2		16.7
Expenditures	(20.8)		(13.4)		(0.9)		(35.1)		(0.3)		(35.4)
December 31, 2019	203.6		89.6		11.8		305.0		4.2		309.2
Additions	30.9		(0.2)		—		30.7		1.7		32.4
Expenditures	(26.1)		(13.2)		(1.2)		(40.5)		(0.5)		(41.0)
December 31, 2020	$	208.4	$	76.2	$	10.6	$	295.2	$	5.4	$	300.6

Summary of Northrop Agreement Activity

The following table summarizes the Northrop Agreement activity (in millions):

Total reimbursable costs under the Northrop Agreement	$	189.7
Amount reimbursed to the Company through December 31, 2020	(143.2)
Receivable from Northrop included in the balance sheet at December 31, 2020	$	46.5

Schedule of Environmental Reserves and Recoveries

The following table summarizes the financial information for the impact of environmental reserves and recoveries to the consolidated statements of operations:

	Year Ended December 31,
	2020		2019		2018
	(In millions)
Expense (benefit) to consolidated statement of operations	$	4.3	$	2.1	$	(36.9)