Restructuring - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	[1]	Dec. 31, 2020	Dec. 31, 2019	[1]	Mar. 31, 2021
Restructuring Cost And Reserve [Line Items]
Restructuring	$ 4,071	$ 4,744		$ 32,747	$ 13,490
Systems & Support [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring				5,725
Aerospace Structures [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring				20,580
Aerospace Structures [Member] | Facility Closures [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring				13,097
Corporate Headquarters [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring				$ 6,442
Forecast [Member]
Restructuring Cost And Reserve [Line Items]
Consulting and severance costs							$ 34,000

[1] As adjusted; refer to Note 1.