Commitments and Contingencies - Guarantees and Contracts (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | 12 Months Ended | ||
---|---|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2018 |
Mar. 31, 2018 |
Mar. 31, 2015 |
|
Contracts with U.S. government agencies or other U.S. government contractors | |||||
Concentration Risk [Line Items] | |||||
Concentration risk, percentage | 96.00% | 97.00% | 96.00% | ||
Unfavorable Regulatory Action | |||||
Loss Contingencies [Line Items] | |||||
Liability for reductions and/or penalties from U.S Government audits | $ 185.5 | $ 185.5 | $ 168.6 | ||
Financial Standby Letter of Credit | |||||
Concentration Risk [Line Items] | |||||
Guarantor obligations, carrying value | 9.6 | 9.6 | 6.3 | ||
Guarantor obligations, reduction to available borrowings | 1.0 | 1.4 | |||
Guarantor obligations, facility | $ 15.0 | ||||
Guarantor obligations, available amount | $ 6.4 | $ 6.4 | $ 10.1 |