BUSINESS COMBINATIONS - Purchase Price Allocation (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Apr. 02, 2018
Business Acquisition [Line Items]
Goodwill		$ 955,881	$ 956,029
Income tax receivable	$ 200
ABILITY Network
Business Acquisition [Line Items]
Cash and cash equivalents				$ 23,850
Accounts receivable				16,739
Income tax receivable				688
Prepaid expenses and other current assets				3,025
Property and equipment				3,095
Goodwill				770,949
Intangible assets				490,000
Other assets				1,252
Accounts payable and accrued expenses				(6,863)
Deferred revenue				(7,000)
Other current liabilities				(507)
Other liabilities				(5,291)
Deferred tax liabilities				(98,887)
Total consideration transferred				$ 1,191,050
Intangible asset adjustment	23,000
Goodwill	1,800
Deferred tax liability	5,000
Shareholder payable adjustment	900
Customer Relationships | ABILITY Network
Business Acquisition [Line Items]
Deferred tax liability	$ 7,500