Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock Shares	Additional Paid-in Capital	Additional Paid-in Capital 2024 Convertible Senior Notes	Additional Paid-in Capital 2.875% Convertible senior notes, due 2028	Additional Paid-in Capital 2.875% Convertible senior notes, due 2024	Additional Paid-in Capital 2.25% Convertible senior notes, due 2024	Retained Earnings	Retained Earnings Cumulative Effect Adjustment Due to Adoption	Accumulated Other Comprehensive (Loss)	Total Equity - Greenbrier	Total Equity - Greenbrier Cumulative Effect Adjustment Due to Adoption	Total Equity - Greenbrier 2024 Convertible Senior Notes	Total Equity - Greenbrier 2.875% Convertible senior notes, due 2028	Total Equity - Greenbrier 2.875% Convertible senior notes, due 2024	Total Equity - Greenbrier 2.25% Convertible senior notes, due 2024	Noncontrolling Interest	Equity Excluding Contingently Redeemable Noncontrolling Interest	Equity Excluding Contingently Redeemable Noncontrolling Interest Cumulative Effect Adjustment Due to Adoption	Equity Excluding Contingently Redeemable Noncontrolling Interest 2024 Convertible Senior Notes	Equity Excluding Contingently Redeemable Noncontrolling Interest 2.875% Convertible senior notes, due 2028	Equity Excluding Contingently Redeemable Noncontrolling Interest 2.875% Convertible senior notes, due 2024	Equity Excluding Contingently Redeemable Noncontrolling Interest 2.25% Convertible senior notes, due 2024	Contingently Redeemable Noncontrolling Interest
Beginning balance at Aug. 31, 2018			$ 442,569					$ 830,898	$ 5,461	$ (23,366)	$ 1,250,101	$ 5,461					$ 134,114	$ 1,384,215	$ 5,461
Beginning balance (in shares) at Aug. 31, 2018		32,191
Beginning balance at Aug. 31, 2018																								$ 29,768
Accounting Standards Update [Extensible List]								Accounting Standards Update 2014-09			Accounting Standards Update 2014-09							Accounting Standards Update 2014-09
Net earnings	$ 105,811							$ 71,076			$ 71,076						39,598	$ 110,674						(4,863)
Other comprehensive income (loss), net	(21,486)									(21,449)	(21,449)						(37)	(21,486)
Noncontrolling interest adjustments								(6,659)			(6,659)						7,402	743						6,659
Joint venture partner distribution declared																	(18,025)	(18,025)
Noncontrolling interest acquired																	1,915	1,915
Restricted stock awards (net of cancellations)			12,077								12,077							12,077
Restricted stock awards (net of cancellations) (in shares)		297
Unamortized restricted stock			(16,801)								(16,801)							(16,801)
Restricted stock amortization			12,321								12,321							12,321
Convertible Senior Notes, equity component, net of tax				$ 3,777									$ 3,777							$ 3,777
Cash dividends								(33,174)			(33,174)							(33,174)
Ending balance at Aug. 31, 2019			453,943					$ 867,602	4,393	(44,815)	$ 1,276,730	4,393					164,967	$ 1,441,697	4,393
Ending Balance (in shares) at Aug. 31, 2019		32,488
Ending Balance at Aug. 31, 2019																								31,564
Accounting Standards Update [Extensible List]								Accounting Standards Update 2016-02			Accounting Standards Update 2016-02							Accounting Standards Update 2016-02
Net earnings	87,586							$ 48,967			$ 48,967						39,066	$ 88,033						(447)
Other comprehensive income (loss), net	(7,982)									(8,002)	(8,002)						20	(7,982)
Noncontrolling interest adjustments																	1,436	1,436
Joint venture partner distribution declared																	(37,552)	(37,552)
Noncontrolling interest acquired																	12,075	12,075
Restricted stock awards (net of cancellations)			2,691								2,691							2,691
Restricted stock awards (net of cancellations) (in shares)		213
Unamortized restricted stock			(4,957)								(4,957)							(4,957)
Restricted stock amortization			8,723								8,723							8,723
Cash dividends								(35,502)			(35,502)							(35,502)
Ending balance at Aug. 31, 2020	$ 1,473,055		460,400					$ 885,460	$ (510)	(52,817)	$ 1,293,043	$ (510)					180,012	$ 1,473,055	$ (510)
Ending Balance (in shares) at Aug. 31, 2020	32,701	32,701
Ending Balance at Aug. 31, 2020																								31,117
Accounting Standards Update [Extensible List]								ASU 2016-13			ASU 2016-13							ASU 2016-13
Net earnings	$ 35,134							$ 32,477			$ 32,477						4,066	$ 36,543						(1,409)
Other comprehensive income (loss), net	9,091									9,104	9,104						(13)	9,091
Noncontrolling interest adjustments																	2,259	2,259
Joint venture partner distribution declared																	(24,645)	(24,645)
Investment by joint venture partner																	7,000	7,000
Restricted stock awards (net of cancellations)			13,486								13,486							13,486
Restricted stock awards (net of cancellations) (in shares)		165
Unamortized restricted stock			(16,794)								(16,794)							(16,794)
Restricted stock amortization			14,704								14,704							14,704
Repurchase of stock	(20,000)		(20,000)								(20,000)							(20,000)
Repurchase of stock (in shares)		(469)
Convertible Senior Notes, equity component, net of tax					$ 56,255		$ (7,383)							$ 56,255		$ (7,383)					$ 56,255		$ (7,383)
Convertible senior notes,due 2028 issuance costs - equitycomponent, net of tax					$ (1,801)									$ (1,801)							$ (1,801)
Convertible senior notes,due 2024 - equity componentextinguishment, net of tax						$ (29,146)									$ (29,146)							$ (29,146)
Cash dividends								(35,687)			(35,687)							(35,687)
Ending balance at Aug. 31, 2021	$ 1,476,427		$ 469,721					$ 881,740		$ (43,713)	$ 1,307,748						$ 168,679	$ 1,476,427
Ending Balance (in shares) at Aug. 31, 2021	32,397	32,397
Ending Balance at Aug. 31, 2021																								$ 29,708