DEBT (Details - Convertible Senior Notes)			3 Months Ended	9 Months Ended
	Jul. 24, 2020 USD ($) day $ / shares Rate shares	May 31, 2017 USD ($) day $ / shares Rate shares	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Annual interest rate on convertible senior notes | Rate	0.50%	0.625%
Amortization of convertible debt discount				$ 12,429,000	$ 8,959,000
Amortization of debt issuance costs				2,241,000	1,463,000
Long-term debt			$ 603,520,000	603,520,000		$ 264,391,000
Repayments of Convertible Debt				233,862,000	0
Reacquisition of equity component			(107,882,000)
Loss on extinguishment of debt				7,768,000	0
2025 Convertible Notes [Member]
Debt Instrument [Line Items]
Stated interest rate | Rate	0.50%
Initial conversion rate, shares per $1,000 principal amount of notes | shares	2.1683
Initial conversion price per share | $ / shares	$ 461.19
Conversion rate, sales price of common stock as a percentage of the conversion price | Rate	130.00%
Threshold trading days | day	5
Threshold consecutive trading days | day	5
Conversion rate, sales price of common stock as a percentage of the conversion price, five business days | Rate	98.00%
Cash repurchase at a price equal to the principal amount of the notes, Percentage | Rate	100.00%
Nonconvertible debt borrowing rate at the date of issuance | Rate	5.30%
Debt component of the principal amount of the Convertible Senior Notes	$ 455,600,000
Equity component of the principal amount of the Convertible Senior Notes	119,400,000
Financing costs related to the issuance of the Convertible Senior Notes	15,100,000
Debt issuance costs, liability component	12,000,000.0		11,591,000	11,591,000
Debt issuance costs, equity component	$ 3,100,000
Total interest expense on the Convertible Senior Notes			4,900,000
Interest expense recognized associated with the coupon rate			500,000
Annual interest rate on convertible senior notes | Rate	0.50%
Amortization of convertible debt discount			4,000,000.0
Amortization of debt issuance costs			400,000
Aggregate principal amount of convertible senior notes			575,000,000	575,000,000
Unamortized debt discount			115,427,000	115,427,000
Long-term debt			447,982,000	447,982,000
2022 Convertible Notes [Member]
Debt Instrument [Line Items]
Initial conversion rate, shares per $1,000 principal amount of notes | shares		4.8163
Initial conversion price per share | $ / shares		$ 207.63
Conversion rate, sales price of common stock as a percentage of the conversion price | Rate		130.00%
Threshold trading days | day		5
Threshold consecutive trading days | day		5
Conversion rate, sales price of common stock as a percentage of the conversion price, five business days | Rate		98.00%
Cash repurchase at a price equal to the principal amount of the notes, Percentage | Rate		100.00%
Nonconvertible debt borrowing rate at the date of issuance | Rate		5.36%
Debt component of the principal amount of the Convertible Senior Notes		$ 238,400,000
Equity component of the principal amount of the Convertible Senior Notes		61,600,000
Financing costs related to the issuance of the Convertible Senior Notes		9,300,000
Debt issuance costs, liability component		7,400,000	1,515,000	1,515,000		3,811,000
Debt issuance costs, equity component		$ 1,900,000
Total interest expense on the Convertible Senior Notes				10,700,000	11,500,000
Interest expense recognized associated with the coupon rate				1,300,000	1,400,000
Annual interest rate on convertible senior notes | Rate		0.625%
Amortization of convertible debt discount				8,400,000	9,000,000.0
Amortization of debt issuance costs				1,000,000.0	$ 1,100,000
Fair value of the Convertible Senior Notes			265,600,000	265,600,000
Aggregate principal amount of convertible senior notes		$ 300,000,000.0	169,692,000	169,692,000		299,991,000
Unamortized debt discount			12,639,000	12,639,000		31,789,000
Long-term debt			155,538,000	155,538,000		$ 264,391,000
Repayments of Convertible Debt	$ 234,000,000.0
Debt repurchase amount	130,300,000
Debt repurchased amount, accrued interest	100,000
Extinguishment of debt	126,000,000.0
Reacquisition of equity component	(107,900,000)
Loss on extinguishment of debt			7,800,000
Convertible Debt [Member] | 2025 Convertible Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 575,000,000.0
Stated interest rate | Rate	0.50%
Fair value of the Convertible Senior Notes			$ 562,100,000	$ 562,100,000
Convertible Debt [Member] | 2025 Notes Under 13-day Purchase Option [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 75,000,000.0