STOCK AWARD PLANS - Total Compensation Expense Recognized (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 10,954,000	$ 14,684,000	$ 22,351,000	$ 31,807,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	5,025,000	4,461,000	10,038,000	8,710,000
Stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	5,291,000	9,584,000	10,694,000	21,328,000
Company expense on ESPP discount
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 638,432	$ 639,000	$ 1,619,000	$ 1,769,000