v3.26.1
Securitization - Schedule of Consolidated Statements of Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Variable Interest Entity [Line Items]        
Operating revenues $ 879,059 $ 838,774 $ 4,184,046 $ 3,965,275
Operation and maintenance expense (223,162) (222,100) (648,762) (662,440)
Amortization expense (201,521) (185,786) (591,853) (549,069)
Interest expense, net (33,144) (41,537) (115,288) (144,476)
Income before income taxes 303,283 230,630 1,540,454 1,264,916
Variable Interest Entity, Primary Beneficiary        
Variable Interest Entity [Line Items]        
Operating revenues 3,379 2,855 10,183 9,199
Operation and maintenance expense (52) (189) (238) (466)
Amortization expense (2,407) (1,646) (7,101) (5,599)
Interest expense, net (920) (1,020) (2,844) (3,134)
Income before income taxes $ 0 $ 0 $ 0 $ 0