Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cumulative-effect adjustment	$ 1,299,092	$ 1,318,013	$ 1,307,383	$ 1,320,907	$ 1,319,793	$ 1,307,474	$ 1,257,318	$ 1,193,344
Cash and cash equivalents, restricted cash	$ 25,900	$ 25,100
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member