Significant Accounting Policies - Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
After Adoption of ASC 326 [Roll Forward]
Allowance for credit losses, beginning of period	$ 48,783	$ 49,773
Additions charged to expense	7,217	10,822
Write-offs, net of recoveries	(11,108)	(11,416)
Allowance for credit losses, end of period	$ 44,892	$ 49,179