Inventories (Details) $ in Thousands	Dec. 31, 2017 USD ($) shipset	Dec. 31, 2016 USD ($)
Schedule of Inventory [Line Items]
Merchandise for resale	$ 151,520	$ 158,618
Raw materials	18,871	20,592
Progress payments	10,810	28,824
Other work in process (including certain general stock materials)	40,445	22,096
Finished goods	25,643	25,309
Total	367,437	393,814
Inventories include amounts associated with matters such as contract changes, negotiated settlements and claims for unanticipated contract costs	4,400	3,600
Segment work in progress	40,445	22,096
Aerospace
Schedule of Inventory [Line Items]
General and administrative costs in inventory, incurred	14,700	13,000
General and administrative costs in inventory, remaining	10,600	11,000
Distribution
Schedule of Inventory [Line Items]
Consignment inventory	5,200	6,400
K-MAX® program
Schedule of Inventory [Line Items]
Inventory, Noncurrent	15,700
Total program inventory	25,500	32,000
SH-2G(I)
Schedule of Inventory [Line Items]
Other work in process (including certain general stock materials)	6,200	7,200
Segment work in progress	6,200	7,200
Inventory, Noncurrent	3,300
A-10 program
Schedule of Inventory [Line Items]
Backlog	$ 1,200
Remaining A-10 shipsets	3
Total program inventory	$ 8,700
Inventory associated with nonrecurring costs	7,000
Other Inventory, Noncurrent	$ 500
Number of shipsets delivered | shipset	170
Shipsets under program of record | shipset	242
U.S. Government contracts
Schedule of Inventory [Line Items]
U.S. Government, net of progress payments of $10,810 and $28,824 in 2017 and 2016, respectively	$ 75,448	85,779
Commercial and other government contracts
Schedule of Inventory [Line Items]
Commercial and other government contracts	$ 55,510	$ 81,420