Commitments and Contingencies - Additional Information (Detail)		6 Months Ended	192 Months Ended
	Jan. 06, 2017 USD ($) Segment	Feb. 28, 2017 USD ($)	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Remedial investigation and feasibility study			$ 110,000,000
Bank and third party warranty and performance guarantee facilities		$ 1,400,000
Equity method investment, percentage of ownership interest		50.00%
Payment to acquire equity method investments		$ 600,000
Note receivable		36,500,000
Mexican Railcar Manufacturing Joint Venture Credit Facility
Commitments and Contingencies Disclosure [Line Items]
Debt outstanding		400,000
Guarantee obligations		200,000
Performance Guarantee
Commitments and Contingencies Disclosure [Line Items]
Letter of credit facility outstanding amount		$ 79,200,000
Portland Harbor Site
Commitments and Contingencies Disclosure [Line Items]
Period for remedial action	13 years
Period for monitoring	30 years
Net present value of remedial alternatives	$ 1,700,000,000
Number of sediment decision units | Segment	13
Portland Harbor Site | Minimum
Commitments and Contingencies Disclosure [Line Items]
Accuracy of cost estimate	(30.00%)
Portland Harbor Site | Maximum
Commitments and Contingencies Disclosure [Line Items]
Accuracy of cost estimate	50.00%
GBW Railcar Services LLC
Commitments and Contingencies Disclosure [Line Items]
Equity method investment, percentage of ownership interest		50.00%
Commercial Litigation in a Foreign Jurisdictions | Pending Litigation
Commitments and Contingencies Disclosure [Line Items]
Adverse judgment		$ 15,000,000