Income Taxes - Summary of Federal statutory income tax rate percentage (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income before income taxes         $ 157,450 $ 103,680 $ 33,044
Federal statutory rate         21.00% 21.00% 21.00%
Theoretical tax expense         $ 33,064 $ 21,773 $ 6,939
State taxes         12,406 9,477 4,366
Other         (1,666) 1,310 1,176
Tax effect of non-deductible expenses:              
Nondeductible share based compensation         3,154
Section 280E permanent differences         50,646 18,026 6,517
Income Tax Reconciliation Total Amount         61,386 28,813 15,212
Income Tax Expense (Benefit) $ 41,603 $ 25,948 $ 105,254 $ 67,116 $ 94,451 $ 50,586 $ 22,151