Summary of Significant Accounting Policies - Allowance for Doubtful Accounts and Credit Memo Reserves (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
BALANCE AT BEGINNING OF THE YEAR	$ 42,856	$ 43,584	$ 46,648
CREDIT MEMOS CHARGED TO REVENUE	55,118	51,846	36,329
ALLOWANCE FOR BAD DEBTS CHARGED TO EXPENSE	34,411	19,389	18,625
DEDUCTIONS AND OTHER	(75,404)	(71,963)	(58,018)
BALANCE AT END OF THE YEAR	$ 56,981	$ 42,856	$ 43,584