Contract Balances (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	$ 43,233
Current Period Provision For Expected Credit Losses	32,224
Write-offs Charged Against Allowance	(39,457)
Balance at End of Period	$ 36,000
Remaining performance obligations	true