Commitments and Contingencies - Summary of Northrop Agreement Activity (Details) - Northrop $ in Millions	Sep. 30, 2021 USD ($)
Contingencies And Commitments [Line Items]
Total reimbursable costs under the Northrop Agreement	$ 189.7
Amount reimbursed to the Company through September 30, 2021	(147.7)
Receivable from Northrop included in the unaudited balance sheet at September 30, 2021	$ 42.0