Condensed Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Millions | Total | Common Stock Shares | Additional Paid-in Capital | 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 | Additional Paid-in Capital Cumulative Effect Adjustment Due to Adoption | Retained Earnings | Retained Earnings Cumulative Effect Adjustment Due to Adoption | Accumulated Other Comprehensive (Loss) | Total Equity - Greenbrier | 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 | Total Equity - Greenbrier Cumulative Effect Adjustment Due to Adoption | Noncontrolling Interest | Equity Excluding Contingently Redeemable Noncontrolling Interest | 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 | Equity Excluding Contingently Redeemable Noncontrolling Interest Cumulative Effect Adjustment Due to Adoption | Contingently Redeemable Noncontrolling Interest |
Beginning balance at Aug. 31, 2020 | | | $ 460.4 | | | | | $ 885.5 | $ (0.5) | $ (52.8) | $ 1,293.1 | | | | $ (0.5) | $ 180 | $ 1,473.1 | | | | $ (0.5) | |
Beginning balance (in shares) at Aug. 31, 2020 | | 32,700 | | | | | | | | | | | | | | | | | | | | |
Beginning balance at Aug. 31, 2020 | | | | | | | | | | | | | | | | | | | | | | $ 31.1 |
Accounting Standards Update [Extensible List] | | | | | | | | ASU 2016-13 | | | ASU 2016-13 | | | | | | ASU 2016-13 | | | | | |
Net earnings | $ (0.5) | | | | | | | $ 0.7 | | | $ 0.7 | | | | | (0.4) | $ 0.3 | | | | | (0.8) |
Other comprehensive income, net | $ 12.8 | | | | | | | | | 12.8 | 12.8 | | | | | | 12.8 | | | | | |
Noncontrolling interest adjustments | | | | | | | | | | | | | | | | 0.3 | 0.3 | | | | | |
Joint venture partner distribution declared | | | | | | | | | | | | | | | | (23) | (23) | | | | | |
Investment by joint venture partner | | | | | | | | | | | | | | | | 7 | 7 | | | | | |
Restricted stock awards (net of cancellations) | | | 15 | | | | | | | | 15 | | | | | | 15 | | | | | |
Restricted stock awards (net of cancellations) (in shares) | | 100 | | | | | | | | | | | | | | | | | | | | |
Unamortized restricted stock | | | (17.9) | | | | | | | | (17.9) | | | | | | (17.9) | | | | | |
Restricted stock amortization | | | 12.5 | | | | | | | | 12.5 | | | | | | 12.5 | | | | | |
Repurchase of stock | | | (20) | | | | | | | | (20) | | | | | | (20) | | | | | |
Repurchase of stock (in shares) | | (400) | | | | | | | | | | | | | | | | | | | | |
Convertible senior notes, due 2028 - equity component, net of tax | | | | $ 56.3 | | | | | | | | $ 56.3 | | | | | | $ 56.3 | | | | |
Convertible senior notes, due 2028 issuance costs - equity component, net of tax | | | | (1.8) | | | | | | | | (1.8) | | | | | | (1.8) | | | | |
Convertible senior notes, due 2024 - equity component extinguishment, net of tax | | | | | $ (28.5) | $ (8.2) | | | | | | | $ (28.5) | $ (8.2) | | | | | $ (28.5) | $ (8.2) | | |
Cash dividends | | | | | | | | (26.7) | | | (26.7) | | | | | | (26.7) | | | | | |
Ending balance at May. 31, 2021 | | | 467.8 | | | | | 859 | | (40) | 1,286.8 | | | | | 163.9 | 1,450.7 | | | | | |
Ending Balance (in shares) at May. 31, 2021 | | 32,400 | | | | | | | | | | | | | | | | | | | | |
Ending Balance at May. 31, 2021 | | | | | | | | | | | | | | | | | | | | | | 30.3 |
Beginning balance at Feb. 28, 2021 | | | 467 | | | | | 848.2 | | (46.7) | 1,268.5 | | | | | 175.9 | 1,444.4 | | | | | |
Beginning balance (in shares) at Feb. 28, 2021 | 32,800 | | | | | | | | | | | | | | | | | | | | | |
Beginning balance at Feb. 28, 2021 | | | | | | | | | | | | | | | | | | | | | | 30 |
Net earnings | $ 20 | | | | | | | 19.7 | | | 19.7 | | | | | | 19.7 | | | | | 0.3 |
Other comprehensive income, net | 6.7 | | | | | | | | | 6.7 | 6.7 | | | | | | 6.7 | | | | | |
Noncontrolling interest adjustments | | | | | | | | | | | | | | | | 1.6 | 1.6 | | | | | |
Joint venture partner distribution declared | | | | | | | | | | | | | | | | (20.6) | (20.6) | | | | | |
Investment by joint venture partner | | | | | | | | | | | | | | | | 7 | 7 | | | | | |
Restricted stock awards (net of cancellations) | | | (0.5) | | | | | | | | (0.5) | | | | | | (0.5) | | | | | |
Restricted stock amortization | | | 3.5 | | | | | | | | 3.5 | | | | | | 3.5 | | | | | |
Repurchase of stock | | | (20) | | | | | | | | (20) | | | | | | (20) | | | | | |
Repurchase of stock (in shares) | | (400) | | | | | | | | | | | | | | | | | | | | |
Convertible senior notes, due 2028 - equity component, net of tax | | | | 56.3 | | | | | | | | 56.3 | | | | | | 56.3 | | | | |
Convertible senior notes, due 2028 issuance costs - equity component, net of tax | | | | $ (1.8) | | | | | | | | $ (1.8) | | | | | | $ (1.8) | | | | |
Convertible senior notes, due 2024 - equity component extinguishment, net of tax | | | | | $ (28.5) | $ (8.2) | | | | | | | $ (28.5) | $ (8.2) | | | | | $ (28.5) | $ (8.2) | | |
Cash dividends | | | | | | | | (8.9) | | | (8.9) | | | | | | | | | | | |
Ending balance at May. 31, 2021 | | | 467.8 | | | | | 859 | | (40) | 1,286.8 | | | | | 163.9 | 1,450.7 | | | | | |
Ending Balance (in shares) at May. 31, 2021 | | 32,400 | | | | | | | | | | | | | | | | | | | | |
Ending Balance at May. 31, 2021 | | | | | | | | | | | | | | | | | | | | | | 30.3 |
Beginning balance at Aug. 31, 2021 | $ 1,476.4 | | $ 469.7 | | | | $ (58.9) | $ 881.7 | $ 4.9 | (43.7) | $ 1,307.7 | | | | (54) | 168.7 | $ 1,476.4 | | | | (54) | |
Beginning balance (in shares) at Aug. 31, 2021 | 32,397 | 32,400 | | | | | | | | | | | | | | | | | | | | |
Beginning balance at Aug. 31, 2021 | | | | | | | | | | | | | | | | | | | | | | 29.7 |
Accounting Standards Update [Extensible List] | | | ASU 2020-06 | | | | | ASU 2020-06 | | | ASU 2020-06 | | | | | | ASU 2020-06 | | | | | |
Net earnings | $ 24.4 | | | | | | | $ 26.7 | | | $ 26.7 | | | | | (0.4) | $ 26.3 | | | | | (1.9) |
Other comprehensive income, net | 7.2 | | | | | | | | | 7.1 | 7.1 | | | | | 0.1 | 7.2 | | | | | |
Noncontrolling interest adjustments | | | $ 2.2 | | | | | | | | 2.2 | | | | | (1.5) | 0.7 | | | | | |
Joint venture partner distribution declared | | | | | | | | | | | | | | | | (10.1) | (10.1) | | | | | |
Restricted stock awards (net of cancellations) | | | 11.9 | | | | | | | | 11.9 | | | | | | 11.9 | | | | | |
Restricted stock awards (net of cancellations) (in shares) | | 200 | | | | | | | | | | | | | | | | | | | | |
Unamortized restricted stock | | | (15.3) | | | | | | | | (15.3) | | | | | | (15.3) | | | | | |
Restricted stock amortization | | | 10.9 | | | | | | | | 10.9 | | | | | | 10.9 | | | | | |
Cash dividends | | | | | | | | (26.8) | | | (26.8) | | | | | | (26.8) | | | | | |
Ending balance at May. 31, 2022 | $ 1,427.2 | $ 32.6 | 420.5 | | | | | 886.5 | | (36.6) | 1,270.4 | | | | | 156.8 | 1,427.2 | | | | | |
Ending Balance (in shares) at May. 31, 2022 | 32,588 | 32,600 | | | | | | | | | | | | | | | | | | | | |
Ending Balance at May. 31, 2022 | | | | | | | | | | | | | | | | | | | | | | 27.8 |
Beginning balance at Feb. 28, 2022 | | | $ 413.4 | | | | $ (0.1) | 892.5 | | (53.3) | $ 1,252.6 | | | | $ (0.1) | 154.1 | $ 1,406.7 | | | | $ (0.1) | |
Beginning balance (in shares) at Feb. 28, 2022 | | 32,600 | | | | | | | | | | | | | | | | | | | | |
Beginning balance at Feb. 28, 2022 | | | | | | | | | | | | | | | | | | | | | | 28.5 |
Accounting Standards Update [Extensible List] | | | ASU 2020-06 | | | | | | | | ASU 2020-06 | | | | | | ASU 2020-06 | | | | | |
Net earnings | $ 7.6 | | | | | | | 3.1 | | | $ 3.1 | | | | | 5.2 | $ 8.3 | | | | | (0.7) |
Other comprehensive income, net | 16.8 | | | | | | | | | 16.7 | 16.7 | | | | | 0.1 | 16.8 | | | | | |
Noncontrolling interest adjustments | 2.2 | | | | | | | | | | 2.2 | | | | | (0.9) | 1.3 | | | | | |
Joint venture partner distribution declared | | | | | | | | | | | | | | | | (1.7) | (1.7) | | | | | |
Restricted stock amortization | | | $ 5 | | | | | | | | 5 | | | | | | 5 | | | | | |
Cash dividends | | | | | | | | (9.1) | | | (9.1) | | | | | | (9.1) | | | | | |
Ending balance at May. 31, 2022 | $ 1,427.2 | $ 32.6 | $ 420.5 | | | | | $ 886.5 | | $ (36.6) | $ 1,270.4 | | | | | $ 156.8 | $ 1,427.2 | | | | | |
Ending Balance (in shares) at May. 31, 2022 | 32,588 | 32,600 | | | | | | | | | | | | | | | | | | | | |
Ending Balance at May. 31, 2022 | | | | | | | | | | | | | | | | | | | | | | $ 27.8 |