Summary of Significant Accounting Policies - Account Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance, beginning of year	$ 6,586	$ 5,230	$ 5,545
Provision for losses	7,287	3,929	4,154
Write-offs	(3,288)	(2,573)	(4,469)
Balance, end of year	14,460	6,586	5,230
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance, beginning of year	0	0
Balance, end of year	$ 3,875	$ 0	$ 0