DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) segment third_party_processor customer	Dec. 31, 2018 USD ($) third_party_processor customer	Dec. 31, 2017 USD ($) customer	Jan. 01, 2019 USD ($)
Concentration Risk [Line Items]
Advertising costs	$ 142,700	$ 101,900	$ 81,900
Restricted cash, current	38,873	33,838
Restricted cash, noncurrent	12,715	15,836
Carrying value of bitcoin held by the Company	1,000	200
Capitalized internally developed software during the period	22,500	24,000	9,800
Amortization expense related to capitalized internally developed software	18,900	10,600	$ 6,600
Operating lease right-of-use assets	113,148
Operating lease liabilities	136,105
Derecognition of build-to-suit lease asset	0	(149,000)
Derecognition of build-to-suit lease liability	0	(149,000)
Asset retirement obligation	3,600
Asset retirement obligation, associated asset net of depreciation	$ 149,194	$ 142,402
Measurement period for business combinations	1 year
Number of reporting units | segment	1
Settlement period for customers payable	1 day
Leasehold Improvements Under Asset Retirement Obligation
Concentration Risk [Line Items]
Asset retirement obligation, associated asset net of depreciation	$ 1,600
Customer Concentration Risk | Net Revenue
Concentration Risk [Line Items]
Number of customers | customer	0	0	0
Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Number of third party processors | third_party_processor	3	3
Third Party Processor One | Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Concentration risk (less than)	48.00%	45.00%
Third Party Processor Two | Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Concentration risk (less than)	29.00%	33.00%
Third Party Processor Three | Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Concentration risk (less than)	9.00%	9.00%
Accounting Standards Update 2016-02
Concentration Risk [Line Items]
Operating lease right-of-use assets				$ 112,000
Operating lease liabilities				135,600
Derecognition of build-to-suit lease asset				149,000
Derecognition of build-to-suit lease liability				$ 149,000
Subscription and services-based revenue
Concentration Risk [Line Items]
Description of timing	The Company considers that it satisfies its performance obligations over time and as such recognizes revenue ratably over the term of the relevant arrangements, which vary from one month to twenty four months for website hosting, and one year to ten years for domain name registration.
Contract with customer, term	1 month
Hardware revenue
Concentration Risk [Line Items]
Description of timing	The Company offers hardware installment sales to customers with terms ranging from three to twenty four months.