Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Deferred Revenue (Details)

v3.21.2
Summary of Significant Accounting Policies - Deferred Revenue (Details) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Dec. 31, 2019
Disaggregation of Revenue [Line Items]      
Deferred revenue $ 848,518 $ 799,276 $ 729,500
Customer agreements      
Disaggregation of Revenue [Line Items]      
Deferred revenue 703,144 666,741  
Customer agreements | Payments received, net      
Disaggregation of Revenue [Line Items]      
Deferred revenue 646,269 614,906  
Customer agreements | Financing component balance      
Disaggregation of Revenue [Line Items]      
Deferred revenue 56,875 51,835  
SREC contracts      
Disaggregation of Revenue [Line Items]      
Deferred revenue 145,374 132,535  
SREC contracts | Payments received, net      
Disaggregation of Revenue [Line Items]      
Deferred revenue 138,022 126,793  
SREC contracts | Financing component balance      
Disaggregation of Revenue [Line Items]      
Deferred revenue $ 7,352 $ 5,742