Share-based compensation - Narratives (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended |
Sep. 28, 2019 | Sep. 29, 2018 | Sep. 28, 2019 | Sep. 29, 2018 | Dec. 30, 2017 |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Share based compensation expense recognized | $ 4.1 | $ 2.3 | $ 10.5 | $ 5.5 | |
Proceeds from stock options exercised | 0 | | 1.6 | | |
—Share options | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Unrecognized compensation relating to non-vested awards | 11.2 | | $ 11.2 | | |
Unrecognized compensation relating to non-vested awards, recognition period (term) | | | 2 years 8 months 12 days | | |
Unrecognized compensation relating to non-vested awards recognizable upon liquidity | 29 | | $ 29 | | |
Aggregate intrinsic value of options exercised | 0 | | $ 2 | | |
RSU's and PRSU's | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Unrecognized compensation relating to non-vested awards, recognition period (term) | | | 2 years 3 months 18 days | | |
Unrecognized compensation relating to non-vested awards other than option | 11.3 | | $ 11.3 | | |
Aggregate intrinsic value of non options vested | $ 0.1 | | $ 0.3 | | |
Omaha Topco Ltd. Stock Incentive Plan | Tranche One | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 20.00% | | |
Omaha Topco Ltd. Stock Incentive Plan | Tranche Two | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 20.00% | | |
Omaha Topco Ltd. Stock Incentive Plan | Tranche Three | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 20.00% | | |
Omaha Topco Ltd. Stock Incentive Plan | Tranche Four | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 20.00% | | |
Omaha Topco Ltd. Stock Incentive Plan | Tranche Five | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 20.00% | | |
Omaha Topco Ltd. Stock Incentive Plan | —RSUs | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | | | 3 years |
Shares granted (shares) | | | | | 76,293 |
Term of award | | | | | 10 years |
Omaha Topco Ltd. Stock Incentive Plan | —Tier I | —Share options | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | | | 5 years |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 3 years | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 4 years | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche One | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche One | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche Two | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche Two | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche Three | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche Three | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Share options | Tranche Four | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —RSUs | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 1 year | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —RSUs | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 3 years | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —RSUs | Tranche One | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —RSUs | Tranche Two | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —RSUs | Tranche Three | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —PRSUs | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Percentage of shares expected to vest upon achievement of average annual adjusted return on invested capital (percentage) | 50.00% | | 50.00% | | |
Percentage of shares expected to vest upon achievement of certain relative shareholders return (percentage) | 50.00% | | 50.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —PRSUs | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 1 year | | |
Total number of shares expected to vest at term of award arrangement (percentage) | | | 0.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —PRSUs | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 3 years | | |
Total number of shares expected to vest at term of award arrangement (percentage) | | | 200.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —PRSUs | Tranche One | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —PRSUs | Tranche Two | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —PRSUs | Tranche Three | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 3 years | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 4 years | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche One | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche One | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche Two | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche Two | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche Three | Minimum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche Three | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —SARs | Tranche Four | Maximum | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 25.00% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Premium-priced options | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting period | | | 3 years | | |
Term of award | | | 10 years | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Premium-priced options | Tranche One | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Premium-priced options | Tranche Two | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |
Gates Industrial Corporation Plc 2018 Omnibus Incentive Plan | —Premium-priced options | Tranche Three | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | |
Vesting percentage | | | 33.33% | | |