Condensed Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock Shares	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Total Equity - Greenbrier	Noncontrolling Interest	Equity Excluding Contingently Redeemable Noncontrolling Interest	Contingently Redeemable Noncontrolling Interest
Beginning balance at Aug. 31, 2022			$ 424.8	$ 897.7	$ (45.6)	$ 1,276.9	$ 152.2	$ 1,429.1
Beginning balance (in shares) at Aug. 31, 2022		32,600,000
Beginning balance at Aug. 31, 2022									$ 27.7
Net earnings	$ 46.2			37.7		37.7	8.4	46.1	0.1
Other comprehensive income (loss), net	22.0				22.0	22.0		22.0
Noncontrolling interest adjustments			(7.9)	(26.3)		(34.2)	(1.6)	(35.8)	26.3
Joint venture partner distribution declared							(10.9)	(10.9)
Restricted stock awards (net of cancellations)			8.9			8.9		8.9
Restricted stock awards (net of cancellations) (in shares)		200,000
Unamortized restricted stock			(11.1)			(11.1)		(11.1)
Stock based compensation expense			8.8			8.8		8.8
Repurchase of stock	$ (49.4)		(49.4)			(49.4)		(49.4)
Repurchase of stock (in shares)	(1,700,000)	(1,700,000)
Cash dividends				(26.9)		(26.9)		(26.9)
Ending balance at May. 31, 2023			374.1	882.2	(23.6)	1,232.7	148.1	1,380.8
Ending Balance (in shares) at May. 31, 2023		31,100,000
Ending Balance at May. 31, 2023									54.1
Beginning balance at Feb. 28, 2023			403.0	896.0	(21.7)	1,277.3	144.6	1,421.9
Beginning balance (in shares) at Feb. 28, 2023		32,300,000
Beginning balance at Feb. 28, 2023									27.5
Net earnings	$ 26.7			21.3		21.3	5.1	26.4	0.3
Other comprehensive income (loss), net	(1.9)				(1.9)	(1.9)		(1.9)
Noncontrolling interest adjustments				(26.3)		(26.3)	0.4	(25.9)	26.3
Joint venture partner distribution declared							(2.0)	(2.0)
Restricted stock awards (net of cancellations)			(0.1)			(0.1)		(0.1)
Unamortized restricted stock			0.3			0.3		0.3
Stock based compensation expense			2.9			2.9		2.9
Repurchase of stock	$ (32.0)		(32.0)			(32.0)		(32.0)
Repurchase of stock (in shares)	(1,200,000)	(1,200,000)
Cash dividends				(8.8)		(8.8)		(8.8)
Ending balance at May. 31, 2023			374.1	882.2	(23.6)	1,232.7	148.1	1,380.8
Ending Balance (in shares) at May. 31, 2023		31,100,000
Ending Balance at May. 31, 2023									54.1
Beginning balance at Aug. 31, 2023	$ 1,410.2		364.4	897.5	(7.3)	1,254.6	155.6	1,410.2
Beginning balance (in shares) at Aug. 31, 2023	30,880,000	30,900,000
Beginning balance at Aug. 31, 2023									55.6
Net earnings	$ 107.4			98.5		98.5	8.2	106.7	0.7
Other comprehensive income (loss), net	(0.7)				(0.7)	(0.7)		(0.7)
Noncontrolling interest adjustments							1.7	1.7
Joint venture partner distribution declared							(7.2)	(7.2)
Restricted stock awards (net of cancellations)			14.5			14.5		14.5
Restricted stock awards (net of cancellations) (in shares)		200,000
Unamortized restricted stock			(19.6)			(19.6)		(19.6)
Stock based compensation expense			12.2			12.2		12.2
Repurchase of stock	$ (1.3)		(1.3)			(1.3)		(1.3)
Repurchase of stock (in shares)	(38,000)
Cash dividends				(29.1)		(29.1)		(29.1)
Ending balance at May. 31, 2024	$ 1,487.4		370.2	966.9	(8.0)	1,329.1	158.3	1,487.4
Ending Balance (in shares) at May. 31, 2024	31,131,000	31,100,000
Ending Balance at May. 31, 2024									56.3
Beginning balance at Feb. 29, 2024			366.1	942.7	(8.9)	1,299.9	154.6	1,454.5
Beginning balance (in shares) at Feb. 29, 2024		31,100,000
Beginning balance at Feb. 29, 2024									56.0
Net earnings	$ 40.6			33.9		33.9	6.4	40.3	0.3
Other comprehensive income (loss), net	$ 0.9				0.9	0.9		0.9
Noncontrolling interest adjustments							0.1	0.1
Joint venture partner distribution declared							(2.8)	(2.8)
Restricted stock awards (net of cancellations)			0.4			0.4		0.4
Restricted stock awards (net of cancellations) (in shares)		0
Unamortized restricted stock			(0.4)			(0.4)		(0.4)
Stock based compensation expense			4.1			4.1		4.1
Repurchase of stock (in shares)	0
Cash dividends				(9.7)		(9.7)		(9.7)
Ending balance at May. 31, 2024	$ 1,487.4		$ 370.2	$ 966.9	$ (8.0)	$ 1,329.1	$ 158.3	$ 1,487.4
Ending Balance (in shares) at May. 31, 2024	31,131,000	31,100,000
Ending Balance at May. 31, 2024									$ 56.3