Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions | Total | Common Stock | Additional Paid-in Capital | Retained Earnings | Accumulated Other Comprehensive Loss | Tennant Company Shareholders' Equity | Noncontrolling Interest |
Beginning balance at Dec. 31, 2017 | $ 298.5 | $ 6.7 | $ 15.1 | $ 297 | $ (22.3) | $ 296.5 | $ 2 |
Balance (in shares) at Dec. 31, 2017 | | 17,881,177 | | | | | |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | 3.3 | $ 0 | 0 | 3.3 | 0 | 3.3 | 0 |
Other Comprehensive (Loss) Income | 5.1 | $ 0 | 0 | 0 | 5.1 | 5.1 | 0 |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) (in shares) | | 29,263 | | | | | |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) | 0.5 | $ 0 | 0.5 | 0 | 0 | 0.5 | 0 |
Share-Based Compensation | 2.7 | 0 | 2.7 | 0 | 0 | 2.7 | 0 |
Dividends paid ($0.22, $0.22, $0.22, $0.21,$0.21, and $0.21) per Common Share | (3.8) | 0 | 0 | (3.8) | 0 | (3.8) | 0 |
Recognition of Noncontrolling Interests | (0.1) | 0 | 0 | 0 | 0 | 0 | (0.1) |
Retained Earnings Adjustment | 1.2 | $ 0 | 0 | 1.2 | 0 | 1.2 | 0 |
Balance (in shares) at Mar. 31, 2018 | | 17,910,440 | | | | | |
Ending balance at Mar. 31, 2018 | 307.4 | $ 6.7 | 18.3 | 297.7 | (17.2) | 305.5 | 1.9 |
Beginning balance at Dec. 31, 2017 | 298.5 | $ 6.7 | 15.1 | 297 | (22.3) | 296.5 | 2 |
Balance (in shares) at Dec. 31, 2017 | | 17,881,177 | | | | | |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | 25.8 | | | | | | |
Purchase of Noncontrolling Owner Interests | 0 | | | | | | |
Balance (in shares) at Sep. 30, 2018 | | 18,122,576 | | | | | |
Ending balance at Sep. 30, 2018 | 309.1 | $ 6.8 | 26.1 | 312.5 | (38.2) | 307.2 | 1.9 |
Beginning balance at Mar. 31, 2018 | 307.4 | $ 6.7 | 18.3 | 297.7 | (17.2) | 305.5 | 1.9 |
Balance (in shares) at Mar. 31, 2018 | | 17,910,440 | | | | | |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | 12.7 | $ 0 | 0 | 12.7 | 0 | 12.7 | 0 |
Other Comprehensive (Loss) Income | (18.2) | $ 0 | 0 | 0 | (18.2) | (18.2) | 0 |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) (in shares) | | 163,273 | | | | | |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) | 2.7 | $ 0.1 | 2.6 | 0 | 0 | 2.7 | 0 |
Share-Based Compensation | 1.4 | 0 | 1.4 | 0 | 0 | 1.4 | 0 |
Dividends paid ($0.22, $0.22, $0.22, $0.21,$0.21, and $0.21) per Common Share | (3.8) | $ 0 | 0 | (3.8) | 0 | (3.8) | 0 |
Balance (in shares) at Jun. 30, 2018 | | 18,073,713 | | | | | |
Ending balance at Jun. 30, 2018 | 302.2 | $ 6.8 | 22.3 | 306.6 | (35.4) | 300.3 | 1.9 |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | 9.7 | 0 | 0 | 9.7 | 0 | 9.7 | 0 |
Other Comprehensive (Loss) Income | (2.8) | $ 0 | 0 | 0 | (2.8) | (2.8) | 0 |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) (in shares) | | 48,863 | | | | | |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) | 1.9 | $ 0 | 1.9 | 0 | 0 | 1.9 | 0 |
Share-Based Compensation | 1.9 | 0 | 1.9 | 0 | 0 | 1.9 | 0 |
Dividends paid ($0.22, $0.22, $0.22, $0.21,$0.21, and $0.21) per Common Share | (3.8) | $ 0 | 0 | (3.8) | 0 | (3.8) | 0 |
Balance (in shares) at Sep. 30, 2018 | | 18,122,576 | | | | | |
Ending balance at Sep. 30, 2018 | 309.1 | $ 6.8 | 26.1 | 312.5 | (38.2) | 307.2 | 1.9 |
Beginning balance at Dec. 31, 2018 | $ 316.3 | $ 6.8 | 28.5 | 316.3 | (37.2) | 314.4 | 1.9 |
Balance (in shares) at Dec. 31, 2018 | 18,125,201 | 18,125,201 | | | | | |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | $ 5.4 | $ 0 | 0 | 5.4 | 0 | 5.4 | 0 |
Other Comprehensive (Loss) Income | (1.3) | $ 0 | 0 | 0 | (1.3) | (1.3) | 0 |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) (in shares) | | 35,338 | | | | | |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) | 0.2 | $ 0 | 0.2 | 0 | 0 | 0.2 | 0 |
Share-Based Compensation | 3.3 | 0 | 3.3 | 0 | 0 | 3.3 | 0 |
Dividends paid ($0.22, $0.22, $0.22, $0.21,$0.21, and $0.21) per Common Share | (4) | 0 | 0 | (4) | 0 | (4) | 0 |
Recognition of Noncontrolling Interests | 0.3 | $ 0 | 0 | 0 | 0 | 0 | 0.3 |
Balance (in shares) at Mar. 31, 2019 | | 18,160,539 | | | | | |
Ending balance at Mar. 31, 2019 | 320.2 | $ 6.8 | 32 | 317.7 | (38.5) | 318 | 2.2 |
Beginning balance at Dec. 31, 2018 | $ 316.3 | $ 6.8 | 28.5 | 316.3 | (37.2) | 314.4 | 1.9 |
Balance (in shares) at Dec. 31, 2018 | 18,125,201 | 18,125,201 | | | | | |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | $ 34.8 | | | | | | |
Purchase of Noncontrolling Owner Interests | $ 0.5 | | | | | | |
Balance (in shares) at Sep. 30, 2019 | 18,254,017 | 18,254,017 | | | | | |
Ending balance at Sep. 30, 2019 | $ 339.8 | $ 6.8 | 39.7 | 339.1 | (47.3) | 338.3 | 1.5 |
Beginning balance at Mar. 31, 2019 | 320.2 | $ 6.8 | 32 | 317.7 | (38.5) | 318 | 2.2 |
Balance (in shares) at Mar. 31, 2019 | | 18,160,539 | | | | | |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | 14.8 | $ 0 | 0 | 14.8 | 0 | 14.8 | 0 |
Other Comprehensive (Loss) Income | 2.4 | $ 0 | 0 | 0 | 2.4 | 2.4 | 0 |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) (in shares) | | 31,947 | | | | | |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) | 0.3 | $ 0 | 0.3 | 0 | 0 | 0.3 | 0 |
Share-Based Compensation | 1.7 | 0 | 1.7 | 0 | 0 | 1.7 | 0 |
Dividends paid ($0.22, $0.22, $0.22, $0.21,$0.21, and $0.21) per Common Share | (4) | 0 | 0 | (4) | 0 | (4) | 0 |
Recognition of Noncontrolling Interests | (0.3) | 0 | 0 | 0 | 0 | 0 | (0.3) |
Purchase of Noncontrolling Owner Interests | 0 | 0 | 0.5 | 0 | 0 | 0.5 | (0.5) |
Other | 0.1 | $ 0 | 0 | 0 | 0 | 0 | 0.1 |
Balance (in shares) at Jun. 30, 2019 | | 18,192,486 | | | | | |
Ending balance at Jun. 30, 2019 | 335.2 | $ 6.8 | 34.5 | 328.5 | (36.1) | 333.7 | 1.5 |
Increase (Decrease) in Stockholders' Equity | | | | | | | |
Net Earnings (Loss) | 14.6 | 0 | 0 | 14.6 | 0 | 14.6 | 0 |
Other Comprehensive (Loss) Income | (11.2) | $ 0 | 0 | 0 | (11.2) | (11.2) | 0 |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) (in shares) | | 61,531 | | | | | |
Issue Stock for Directors, Employee Benefit and Stock Plans, net of related tax withholdings (6,952, 3,310, 1,560, 4,151, 3,360, and 1,327 shares) | 1.5 | $ 0 | 1.5 | 0 | 0 | 1.5 | 0 |
Share-Based Compensation | 3.7 | 0 | 3.7 | 0 | 0 | 3.7 | 0 |
Dividends paid ($0.22, $0.22, $0.22, $0.21,$0.21, and $0.21) per Common Share | $ (4) | $ 0 | 0 | (4) | 0 | (4) | 0 |
Balance (in shares) at Sep. 30, 2019 | 18,254,017 | 18,254,017 | | | | | |
Ending balance at Sep. 30, 2019 | $ 339.8 | $ 6.8 | $ 39.7 | $ 339.1 | $ (47.3) | $ 338.3 | $ 1.5 |