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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Number of shares authorized for issuance under share-based payment arrangement.

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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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Percentage of vesting of award under share-based payment arrangement.

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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 fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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SHARE-BASED COMPENSATION - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	14,250,000
Awards outstanding and issued (in shares)	12,622,117
Unrecognized compensation cost	$ 50,100,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percent	85.00%
Number of shares available for grant (in shares)	241,902
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	1 year
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares granted	$ 14,600,000	$ 19,300,000
Unrecognized compensation cost	48,100,000
Restricted stock \| 2017 Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares granted	32,600,000
Performance-based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares granted	8,100,000	800,000
Allocated share-based compensation expense		1,100,000
Unrecognized compensation cost	2,000,000.0
Performance-based restricted stock \| 2015 Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares granted			$ 17,400,000
Performance-based restricted stock \| 2017 Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	12,100,000
Allocated share-based compensation expense	1,000,000.0	$ 1,800,000
Nonvested options forfeited	5,400,000
Unrecognized compensation cost	13,800,000
Performance-based restricted stock \| 2018 Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	25,100,000
Fair value of shares granted	31,200,000
Allocated share-based compensation expense	0
Nonvested options forfeited	6,100,000
Performance-based restricted stock \| 2020 Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	8,100,000
Fair value of shares granted	$ 8,100,000
Stock Option 25
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	4 years
Stock Option 25 \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	4 years
Stock Option 25 \| Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	1 year
Stock Option 75
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	3 years
Percent of awards vesting after initial year	75.00%
Stock Option 75 \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	3 years
Periodic Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percent (at least)	100.00%
Periodic Vesting \| Employee Director Consultant Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award (no later than)	10 years
Periodic Vesting \| Stock Option 25
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage	25.00%
Periodic Vesting \| Stock Option 25 \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage	25.00%
Minimum \| Performance-based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	1 year
Maximum \| Performance-based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, outstanding, weighted average remaining contractual term	2 years