Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Contingently Redeemable Noncontrolling Interest	Common Stock Shares	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total Attributable to Greenbrier	Attributable to Noncontrolling Interest	Equity Excluding Contingently Redeemable Noncontrolling Interest [Member]	2024 Convertible Senior Notes Additional Paid-in Capital	2024 Convertible Senior Notes Total Attributable to Greenbrier	2024 Convertible Senior Notes Equity Excluding Contingently Redeemable Noncontrolling Interest [Member]	2024 Convertible Senior Notes Issuance Costs Additional Paid-in Capital	2024 Convertible Senior Notes Issuance Costs Total Attributable to Greenbrier	2024 Convertible Senior Notes Issuance Costs Equity Excluding Contingently Redeemable Noncontrolling Interest [Member]
Beginning balance (in shares) at Aug. 31, 2014			27,364
Beginning balance at Aug. 31, 2014				$ 235,763	$ 282,559	$ (6,932)	$ 511,390	$ 62,331	$ 573,721
Net earnings	$ 265,309				192,832		192,832	72,477	265,309
Other comprehensive income (loss), net	(14,429)					(14,273)	(14,273)	(156)	(14,429)
Noncontrolling interest adjustments								17,215	17,215
Purchase of noncontrolling interest								(80)	(80)
Joint venture partner distribution declared								(21,136)	(21,136)
Restricted stock awards (net of cancellations) (in shares)			(15)
Restricted stock awards (net of cancellations)				22,622			22,622		22,622
Unamortized restricted stock				(24,477)			(24,477)		(24,477)
Restricted stock amortization				19,459			19,459		19,459
Excess tax benefit from restricted stock awards				2,908			2,908		2,908
Conversion of convertible notes, net of debt issuance costs (in shares)			2,945
Conversion of convertible notes, net of debt issuance costs				109,387			109,387		109,387
Dividends					(16,792)		(16,792)		(16,792)
Repurchase of stock				(70,218)			(70,218)		(70,218)
Repurchase of stock, shares			(1,387)
Ending Balance (in shares) at Aug. 31, 2015			28,907
Ending Balance at Aug. 31, 2015				295,444	458,599	(21,205)	732,838	130,651	863,489
Ending Balance at Aug. 31, 2016		$ (2,140)
Net earnings	284,824				183,213		183,213	101,611	284,824
Other comprehensive income (loss), net	$ (5,586)					(5,548)	(5,548)	(38)	(5,586)
Noncontrolling interest adjustments								526	526
Purchase of noncontrolling interest								(1,195)	(1,195)
Joint venture partner distribution declared								(94,439)	(94,439)
Investment by joint venture partner								5,400	5,400
Restricted stock awards (net of cancellations) (in shares)			353
Restricted stock awards (net of cancellations)				6,055			6,055		6,055
Unamortized restricted stock				(11,555)			(11,555)		(11,555)
Restricted stock amortization				22,502			22,502		22,502
Excess tax benefit from restricted stock awards				2,813			2,813		2,813
Dividends					(23,634)		(23,634)		(23,634)
Repurchase of stock				(32,373)			(32,373)		(32,373)
Repurchase of stock, shares			(1,055)
Ending Balance (in shares) at Aug. 31, 2016	28,205		28,205
Ending Balance at Aug. 31, 2016	$ 1,016,827			282,886	618,178	(26,753)	874,311	142,516	1,016,827
Contingently redeemable noncontrolling interest		38,288
Ending Balance at Aug. 31, 2017		$ 36,148
Net earnings	160,462				116,067		116,067	46,535	162,602
Other comprehensive income (loss), net	20,496					20,474	20,474	22	20,496
Noncontrolling interest adjustments								(677)	(677)
Joint venture partner distribution declared								(28,027)	(28,027)
Acquisition of minority interest								394	394
Restricted stock awards (net of cancellations) (in shares)			298
Restricted stock awards (net of cancellations)				5,520			5,520		5,520
Unamortized restricted stock				(10,734)			(10,734)		(10,734)
Restricted stock amortization				19,826			19,826		19,826
Tax deficiency from restricted stock awards	$ (2,339)			(2,339)			(2,339)		(2,339)
Dividends					(25,142)		(25,142)		(25,142)
2024 Convertible Senior Notes - equity component, net of tax										$ 20,818	$ 20,818	$ 20,818	$ (671)	$ (671)	$ (671)
Ending Balance (in shares) at Aug. 31, 2017	28,503		28,503
Ending Balance at Aug. 31, 2017	$ 1,178,893			$ 315,306	$ 709,103	$ (6,279)	$ 1,018,130	$ 160,763	$ 1,178,893