Revision to Previously Reported Financial Information - Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net cash flows provided (used) by operating activities	$ 115,629	$ 143,223
Net cash flows provided (used) by investing activities	(34,160)	(4,503)
Cash and cash equivalents	$ 921,178	545,849	$ 670,980	$ 619,683
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net cash flows provided (used) by operating activities		143,991
Net cash flows provided (used) by investing activities		(3,851)
Cash and cash equivalents		547,270
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net cash flows provided (used) by operating activities		(768)
Net cash flows provided (used) by investing activities		(652)
Cash and cash equivalents		$ (1,421)