Discount percentage on purchase of stock.

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Share-based Compensation Arrangement by Share-based Payment Award, Minimum Employee Subscription Rate

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value of stock purchase right percentage of put option.

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Aggregate number of common shares reserved for future issuance.

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Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

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Amount of discretionary contributions made by an employer to a defined contribution plan.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.

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EMPLOYEE BENEFIT PLANS - Narrative (Details) - USD ($)	12 Months Ended
EMPLOYEE BENEFIT PLANS - Narrative (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	0	0
Weighted-average remaining contractual term (in years)	1 year 2 months 12 days
Aggregate intrinsic value	$ 3,300,000
Intrinsic value of options exercised	2,100,000	$ 200,000	$ 1,800,000
Fair value of options vested	0	0	100,000
Payments of dividends	0	0	0
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value	18,300,000	$ 15,500,000	9,700,000
Unrecognized share-based compensation cost	$ 18,300,000
Weighted-average period (in years)	1 year 6 months
Weighted average fair value (in dollars per share)	$ 7.90
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price (in dollars per share)	$ 3.15	$ 5.80
Income tax benefit from stock option exercises	$ 0	$ 0	$ 0
Employee stock purchase rights under ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share exercise price (in percent)	85.00%
Common stock reserved for issuance (in shares)	1,184,205
Employees payroll deductions minimum (in percent)	1.00%
Employees payroll deductions maximum (in percent)	10.00%
Common stock issued under the 2002 ESPP (in shares)	1,024,244	1,036,543	1,037,366
Stock contributions value under 2002 ESPP	$ 5,100,000	$ 4,500,000	$ 4,100,000
Discount on the purchase of the stock (in percent)	15.00%
Fair value of the put option (in percent)	15.00%
Weighted average fair value (in dollars per share)	$ 2.24	$ 1.80	$ 1.33
1995 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share exercise price (in percent)	100.00%
Expiration period (in years)	7 years
Common stock reserved for issuance (in shares)	7,317,622
Shares available for grant (in shares)	3,223,471
1995 Stock Plan \| Incentive Stock Option or Non-statutory Stock Option with Exercise Price less than 100% Fair Value of Common Stock on Grant Date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0
1995 Stock Plan \| RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price (in dollars per share)	$ 0
1995 Stock Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	2 years
1995 Stock Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years
2002 Director Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share exercise price (in percent)	100.00%
Common stock reserved for issuance (in shares)	800,182
Shares available for grant (in shares)	628,749
2002 Director Plan \| RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price (in dollars per share)	$ 0
Vesting period (in years)	1 year
2002 Director Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Expiration period (in years)	7 years
TVN
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contributions made	$ 0
Expected employer contributions in 2022	$ 0