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EMPLOYEE BENEFIT PLANS - Other information (Details) - USD ($) $ / shares in Units, $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Jan. 31, 2019 | Jan. 31, 2018 | Jan. 31, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Employee benefits |  |  |  |  |  |
Unexercised stock options outstanding |  |  |  | 0 |  |
Stock Options |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Total remaining compensation cost related to unvested share options |  |  |  | $ 0.0 |  |
Restricted Stock |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Issued |  |  |  | 6,300,000 |  |
Total remaining compensation cost related to unvested share options |  |  |  | $ 3.9 |  |
Weighted average remaining contractual life |  |  |  | 1 year 7 months 6 days |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |  |  |  | $ 38.35 |  |
Stock based compensation expense |  |  |  | $ 4.8 | $ 4.3 | $ 4.0
Initial performance period to make adjustments |  |  |  | 1 year |  |
Restricted Stock | Minimum |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Vesting period |  |  |  | 3 years |  |
Restricted Stock | Maximum |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Vesting period |  |  |  | 4 years |  |
Long Term Incentive Plan |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Issued |  |  |  | 2,900,000 |  |
Total remaining compensation cost related to unvested share options |  |  |  | $ 9.8 |  |
Shares available for issuance under plan |  |  |  | 6,300,000 |  |
Weighted average remaining contractual life |  |  |  | 1 year 4 months 24 days |  |
Number of share options exercisable |  |  |  | 858,000 | 611 |
Stock based compensation expense |  |  |  | $ 12.4 | $ 9.9 | 8.9
Short Term Incentive Plan |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Stock based compensation expense |  |  |  |  | $ 0.0 | $ 0.0
2017 LTIP |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  |  |  |  | 100.00%
FFO as Adjusted Per Share, Value |  |  | $ 16.63 |  |  |
Share Price |  |  | $ 35.95 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate |  |  | 23.00% |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  |  | 7.50% |  |  |
2017 LTIP | First portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  | 30.00% |  |  |
FFO as Adjusted Per Share, Value |  |  | $ 16.18 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  |  | 10.00% |  |  |
Vesting period |  |  | 1 year |  |  |
2017 LTIP | 50% vesting out of first portion of LTI Award |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  | 50.00% |  |  |
2017 LTIP | Balance 50% vesting out of first portion of LTI Award |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  | 50.00% |  |  |
2017 LTIP | Second portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 100.00% | 10.00% |  |  |
Vesting period |  |  | 3 years |  |  | 3 years
2017 LTIP | Third portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  | 60.00% |  |  |
Vesting period |  |  | 3 years |  |  | 3 years
2017 LTIP | Relative component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value |  |  | $ 20.54 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  |  | 7.50% |  |  |
2017 LTIP | Absolute component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value |  |  | $ 14.71 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  |  | 7.50% |  |  |
2017 LTIP | Restricted Stock | Relative component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |  |  | $ 44.26 |  |  |
2017 LTIP | Restricted Stock | Absolute component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |  |  | $ 31.40 |  |  |
2018 LTIP |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  |  |  | 100.00% |
FFO as Adjusted Per Share, Value |  | $ 18.08 |  |  |  |
Share Price |  | $ 38.06 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate |  | 17.00% |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  | 5.00% |  |  |  |
Vesting period |  | 3 years |  |  |  |
2018 LTIP | First portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 30.00% |  |  |  |
FFO as Adjusted Per Share, Value |  | $ 17.13 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  | 10.00% |  |  |  |
Vesting period |  | 1 year |  |  |  |
2018 LTIP | 50% vesting out of first portion of LTI Award |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 50.00% |  |  |  |
2018 LTIP | Balance 50% vesting out of first portion of LTI Award |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 50.00% |  |  |  |
2018 LTIP | Second portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 15.00% |  |  |  |
Vesting period |  | 3 years |  | 3 years |  |
2018 LTIP | Third portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 55.00% |  |  |  |
Vesting period |  | 3 years |  | 3 years |  |
2018 LTIP | Relative component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value |  | $ 20.12 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  | 5.00% |  |  |  |
2018 LTIP | Absolute component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value |  | $ 19.35 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate |  |  |  |  | 17.00% |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  | 5.00% |  |  |  |
2018 LTIP | Restricted Stock | Relative component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |  | $ 42.18 |  |  |  |
2018 LTIP | Restricted Stock | Absolute component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value |  | $ 40.49 |  |  |  |
2019 LTIP | Restricted Stock | Relative component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ 43.63 |  |  |  |  |
2019 LTIP | Restricted Stock | Absolute component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | 43.42 |  |  |  |  |
2019 LTIP | Long Term Incentive Plan |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  |  |  | 100.00% |  |
FFO as Adjusted Per Share, Value | 18.24 |  |  |  |  |
Share Price | $ 38.39 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate | 21.00% |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date | 5.00% |  |  |  |  |
Vesting period | 3 years |  |  |  |  |
2019 LTIP | Long Term Incentive Plan | First portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 30.00% |  |  |  |  |
FFO as Adjusted Per Share, Value | $ 17.47 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date | 9.00% |  |  |  |  |
Vesting period | 1 year |  |  |  |  |
2019 LTIP | Long Term Incentive Plan | 50% vesting out of first portion of LTI Award |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 50.00% |  |  |  |  |
2019 LTIP | Long Term Incentive Plan | Balance 50% vesting out of first portion of LTI Award |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 50.00% |  |  |  |  |
2019 LTIP | Long Term Incentive Plan | Second portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 15.00% |  |  |  |  |
Vesting period | 3 years |  |  | 3 years |  |
2019 LTIP | Long Term Incentive Plan | Third portion of awards |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 55.00% |  |  |  |  |
Vesting period | 3 years |  |  | 3 years |  |
2019 LTIP | Long Term Incentive Plan | Relative component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value | $ 20.89 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date | 5.00% |  |  |  |  |
2019 LTIP | Long Term Incentive Plan | Absolute component |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value | $ 20.79 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate |  |  |  | 21.00% |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date | 5.00% |  |  |  |  |
2019 LTIP | Short Term Incentive Plan |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
FFO as Adjusted Per Share, Value | $ 33.40 |  |  |  |  |
Stock based compensation expense |  |  |  | $ 7.2 |  |
Vesting period | 1 year |  |  |  |  |
Initial performance period to make adjustments | 1 year |  |  |  |  |
Unrecognized compensation expense |  |  |  | $ 0.0 |  |
Long Term Incentive Plan |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Shares reserved for issuance under plan |  |  |  | 19,000,000.0 |  |
Profit Sharing Plan |  |  |  |  |  |
Employee benefits |  |  |  |  |  |
Aggregate provisions for contributions |  |  |  | $ 1.2 | $ 1.3 | $ 1.3

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