Commitments and Contingencies - Summary of Northrop Agreement Activity (Details) - Northrop $ in Millions	Mar. 31, 2017 USD ($)
Contingencies And Commitments [Line Items]
Total reimbursable costs under the Northrop Agreement	$ 189.7
Amount reimbursed to the Company through March 31, 2017	(120.7)
Potential future cost reimbursements available	69.0
Less: Receivable from Northrop included in the unaudited condensed consolidated balance sheet as of March 31, 2017	(67.7)
Potential future recoverable amounts available under the Northrop Agreement	1.3
Maximum
Contingencies And Commitments [Line Items]
Total reimbursable costs under the Northrop Agreement	$ 189.7