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STOCK-BASED COMPENSATION PLANS (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
STOCK-BASED COMPENSATION PLANS |  |  |  |
Recognized employee stock-based compensation expense | $ 9,100,000 | $ 7,500,000 | $ 6,500,000 |
Employee Stock Purchase Plan |  |  |  |
STOCK-BASED COMPENSATION PLANS |  |  |  |
Shares available for grant | 640,318 |  |  |
Weighted-Average Grant Date Fair Value |  |  |  |
Shares available under the plan | 3,600,000 |  |  |
Offering period for the plan (in months) | 3 months |  |  |
Period of interval between occurrence of purchases (in months) | 3 months |  |  |
IRS regulated cap for payroll deduction to purchase common stock | $ 25,000 |  |  |
Purchase price expressed as a percentage of fair market value of common stock (as a percent) | 90.00% |  |  |
Shares issued under ESPP | 206,806 |  |  |
Shares available for purchase under ESPP | 640,318 |  |  |
Minimum | Employee Stock Purchase Plan |  |  |  |
Weighted-Average Grant Date Fair Value |  |  |  |
Eligible service period of employees per week to participate in the plan (in hours) | 20 hours |  |  |
Eligible service period of employees in a calendar year to participate in the plan (in months) | 5 months |  |  |
Percentage of employees' eligible earnings as payroll deduction to purchase common stock | 1.00% |  |  |
Maximum | Employee Stock Purchase Plan |  |  |  |
Weighted-Average Grant Date Fair Value |  |  |  |
Percentage of employees' eligible earnings as payroll deduction to purchase common stock | 10.00% |  |  |
Restricted Stock Units |  |  |  |
Weighted-Average Grant Date Fair Value |  |  |  |
Weighted-average period to recognize unrecognized compensation cost | 1 year 6 months |  |  |
Incentive Plan |  |  |  |
STOCK-BASED COMPENSATION PLANS |  |  |  |
Additional shares authorized |  |  |  | 5,500,000
Shares available for grant | 2,231,197 |  |  |
Weighted-Average Grant Date Fair Value |  |  |  |
Total fair value RSUs vested (in dollars) | $ 6,100,000 | $ 4,700,000 | $ 9,000,000.0 |
Unrecognized compensation cost related to the RSUs | $ 11,700,000 |  |  |
Shares available under the plan | 2,900,000 |  |  |
Incentive Plan | Maximum |  |  |  |
STOCK-BASED COMPENSATION PLANS |  |  |  |
Expiration period (in years) | 10 years |  |  |
Incentive Plan | Restricted Stock Units |  |  |  |
STOCK-BASED COMPENSATION PLANS |  |  |  |
Percentage of vesting through the fourth anniversary of the grant date | 100.00% |  |  |
Percentage of vesting upon a termination of employment | 100.00% |  |  |
RSU |  |  |  |
Non-vested at the beginning of the period (in shares) | 3,820,000 | 4,020,000 | 6,866,000 |
Granted (in shares) | 2,295,000 | 1,527,000 | 1,112,000 |
Vested (in shares) | (1,409,000) | (1,610,000) | (3,680,000) |
Forfeited (in shares) | (785,000) | (117,000) | (278,000) |
Non-vested at the end of the period (in shares) | 3,921,000 | 3,820,000 | 4,020,000 | 6,866,000
Weighted-Average Grant Date Fair Value |  |  |  |
Non-vested at the beginning of the period (in dollars per share) | $ 4.68 | $ 3.20 | $ 2.31 |
Granted (in dollars per share) | 4.61 | 6.57 | 6.07 |
Vested (in dollars per share) | 4.35 | 2.88 | 2.46 |
Forfeited (in dollars per share) | 2.87 | 3.37 | 2.51 |
Non-vested at the end of the period (in dollars per share) | $ 5.10 | $ 4.68 | $ 3.20 | $ 2.31

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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(03) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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