Commitments and Contingencies - Narrative - Environmental Reserves and Estimated Recoveries (Details) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2017	Jun. 30, 2020	Nov. 30, 2003
Site Contingency [Line Items]
Environmental remediation cost expected period (years)		15 years
Non-reimbursable percentage of environmental costs		12.00%
Northrop
Site Contingency [Line Items]
Percentage of environmental remediation costs recoverable		88.00%
Current annual billing limitation		$ 6,000,000.0
Reimbursable remediation cost		$ 189,700,000
Atlantic Research Corporation
Site Contingency [Line Items]
Pre-close environmental costs	$ 20,000,000.0		$ 20,000,000.0