Summary of Significant Accounting Policies - Additional Disclosures (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($) activity segment	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jan. 01, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of business activities | activity	1
Number of operating segments | segment	1
Adjustment to retained earnings	$ (619,712)	$ (485,613)	$ (623,161)	$ (488,117)		$ (466,941)	$ (454,183)	$ (436,663)	$ (422,415)
Accounting Standards Update		us-gaap:AccountingStandardsUpdate201613Member
Accounts receivable, net	112,817	$ 105,901
Allowance for credit losses	2,133	2,946	2,076	2,055	$ 1,892
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings		1,198
Retained Earnings (Accumulated Deficit)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings	$ (36,974)	(57,522)	$ (45,789)	$ (57,749)		$ (47,833)	$ (36,350)	$ (19,762)	$ (9,064)
Retained Earnings (Accumulated Deficit) | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings		$ 1,198