Commitments and Contingencies - Additional Information (Detail)		3 Months Ended	180 Months Ended
	Jun. 08, 2016 USD ($) Segment	Nov. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Aug. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Remedial investigation and feasibility study			$ 110,000,000
Bank and third party warranty and performance guarantee facilities		$ 2,100,000
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		700,000
Guarantee obligations		300,000
Performance Guarantee
Commitments and Contingencies Disclosure [Line Items]
Letter of credit facility outstanding amount		$ 81,300,000
Portland Harbor Site
Commitments and Contingencies Disclosure [Line Items]
Discount rate	7.00%
Portland Harbor Site | Minimum
Commitments and Contingencies Disclosure [Line Items]
Period for remedial action	4 years
Undiscounted costs for remedial alternatives	$ 642,000,000
Net present value of remedial alternatives	$ 451,000,000
Portland Harbor Site | Maximum
Commitments and Contingencies Disclosure [Line Items]
Period for remedial action	62 years
Undiscounted costs for remedial alternatives	$ 10,200,000,000
Net present value of remedial alternatives	$ 9,400,000,000
Area Of Willamette River Adjacent to the Company's Portland, Oregon Manufacturing Facility
Commitments and Contingencies Disclosure [Line Items]
Period for remedial action	7 years
Number of sediment decision units | Segment	13
Period for monitoring	30 years
Area Of Willamette River Adjacent to the Company's Portland, Oregon Manufacturing Facility | Minimum
Commitments and Contingencies Disclosure [Line Items]
Undiscounted costs for remedial alternatives	$ 1,100,000,000
Net present value of remedial alternatives	$ 746,000,000
Accuracy of cost estimate	(30.00%)
Area Of Willamette River Adjacent to the Company's Portland, Oregon Manufacturing Facility | Maximum
Commitments and Contingencies Disclosure [Line Items]
Undiscounted costs for remedial alternatives	$ 1,200,000,000
Net present value of remedial alternatives	$ 811,000,000
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%
Additional cash contributions in 2017				$ 1,900,000
Commercial Litigation in a Foreign Jurisdictions | Pending Litigation
Commitments and Contingencies Disclosure [Line Items]
Adverse judgment		$ 15,000,000