Revenue Recognition and Contracts with Customers - Schedule of Disaggregated Net Sales Satisfied Overtime and at a Point in Time (Excluding Intercompany Sales) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Amortization of acquired contract liabilities	$ 17,163	$ 22,616		$ 28,150	$ 39,556
Revenues	481,815	772,110	[1]	976,892	1,502,341	[1]
Systems & Support [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers	250,093	341,785		484,389	646,427
Amortization of acquired contract liabilities	3,544	9,624		7,263	17,749
Revenues excluding intercompany sales	253,637	351,409		491,652	664,176
Systems & Support [Member] | Transferred over Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers	102,807	139,354		206,155	268,596
Systems & Support [Member] | Transferred at Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers	147,286	202,431		278,234	377,831
Aerospace Structures [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers	214,559	407,709		464,353	816,358
Amortization of acquired contract liabilities	13,619	12,992		20,887	21,807
Revenues excluding intercompany sales	228,178	420,701		485,240	838,165
Aerospace Structures [Member] | Transferred over Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers	204,180	372,247		447,819	744,484
Aerospace Structures [Member] | Transferred at Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contracts with customers	$ 10,379	$ 35,462		$ 16,534	$ 71,874

[1] As adjusted; refer to Note 1.