DEBT - Narrative (Details)		3 Months Ended			9 Months Ended
	Feb. 04, 2020 USD ($) $ / shares	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Feb. 03, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Term loan component of senior credit facility		$ 22,500,000			$ 22,500,000			$ 45,000,000
Carrying amount, liability component		469,898,000			469,898,000			0
Cost of call transactions					104,248,000	$ 0
Proceeds from warrant transactions					44,563,000	$ 0
Securitization program outstanding borrowings, maximum limit				$ 150,000,000.0
Securitization program, term				3 years
Long-term borrowings under securitization facility		$ 92,300,000			$ 92,300,000			$ 104,500,000
Weighted average interest rate, accounts receivable securitization revolving loan facility		1.40%			1.40%			2.80%
Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Securitization facility, outstanding borrowings, fair value		$ 92,800,000			$ 92,800,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 1,300,000,000
Line of credit facility outstanding		$ 97,500,000			$ 97,500,000			$ 375,000,000.0
Weighted average interest rate on debt		1.50%			1.50%			3.20%
Revolving Credit Facility | Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Line of credit facility, fair value of amount outstanding		$ 94,600,000			$ 94,600,000
Standby Letters of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity							60,000,000
Swingline Loans
Debt Instrument [Line Items]
Maximum borrowing capacity							60,000,000
Senior Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity							2,200,000,000
Incremental financing costs capitalized							4,600,000
Previously capitalized financing costs, written-off			$ 1,200,000
Incremental financing cost expense		3,300,000
Senior Credit Facility | Overnight Federal Funds
Debt Instrument [Line Items]
Interest rates available					0.50%
Senior Credit Facility | One Month Eurodollar Rate
Debt Instrument [Line Items]
Interest rates available					1.00%
Senior Credit Facility | Minimum
Debt Instrument [Line Items]
Line of credit, commitment fee percentage					0.15%
Senior Credit Facility | Minimum | Eurodollar
Debt Instrument [Line Items]
Interest rates available					1.00%
Senior Credit Facility | Maximum
Debt Instrument [Line Items]
Line of credit, commitment fee percentage					0.30%
Senior Credit Facility | Maximum | Eurodollar
Debt Instrument [Line Items]
Interest rates available					2.25%
Senior Credit Facility | Standby Letters of Credit
Debt Instrument [Line Items]
Line of credit facility outstanding		0			$ 0
Letters of credit outstanding		1,600,000			1,600,000			$ 800,000
Term Loan Facility | Secured Debt
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 877,500,000
Line of credit facility outstanding		$ 877,500,000			$ 877,500,000			$ 877,500,000
Weighted average interest rate on debt		1.50%			1.50%			3.20%
Term loan component of senior credit facility		$ 22,500,000			$ 22,500,000
Term Loan Facility | Secured Debt | Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Line of credit facility, fair value of amount outstanding		853,700,000			853,700,000
2025 Notes | Convertible Debt
Debt Instrument [Line Items]
Incremental financing costs capitalized	$ 13,200,000
Convertible notes, maximum borrowing capacity	$ 575,000,000.0	575,000,000.0			575,000,000.0
Convertible notes, interest rate	0.50%
Debt proceeds, classified as equity at time of offering	$ 104,500,000
Effective interest rate	4.20%
Carrying amount, liability component		481,500,000			481,500,000
Unamortized discount		93,500,000			93,500,000
Fair value		$ 541,800,000			541,800,000
Initial conversion rate	13.5739
Initial conversion price (in dollars per share) | $ / shares	$ 73.67
Maximum selling price of the company's common stock of the conversion price	130.00%
Maximum average conversion value of notes	98.00%
Redemption price, percentage	100.00%
Warrant strike price (in dollars per share) | $ / shares	$ 113.34
Cash interest					1,900,000
Amortization of discount					11,100,000
Interest expense					13,000,000.0
2025 Notes | Convertible Debt | Call Option
Debt Instrument [Line Items]
Cost of call transactions					104,200,000
Proceeds from warrant transactions					$ 44,500,000
Initial strike price (in dollars per share) | $ / shares	$ 73.67