v3.26.3
Fair Value of ETC - Summary of changes in quantity of ETC and the respective fair value (Detail)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
ETC
Sep. 30, 2025
USD ($)
ETC
Sep. 30, 2026
USD ($)
ETC
Sep. 30, 2025
USD ($)
ETC
Fair Value Disclosures [Abstract]        
Investment Owned, Balance | ETC     10,985,516.92607291 11,263,626.2550315
ETC contributed | ETC     0 0
ETC distributed for expenses | ETC     (203,512.45565786) (208,664.57666045)
Net realized gain | ETC     0 0
Net change in unrealized appreciation/depreciation | ETC     0 0
Investment Owned, Balance | ETC 10,782,004.47041505 11,054,961.67837105 10,782,004.47041505 11,054,961.67837105
Investment Owned, Fair Value | $     $ 126,004 $ 283,055
ETC contributed | $     0 0
ETC distributed for expenses | $     (1,714) (4,130)
Net realized (loss) gain | $ $ (17) $ 912 177 2,554
Net change in unrealized appreciation/depreciation | $ 20,161 17,154 (29,521) (78,289)
Investment Owned, Fair Value | $ $ 94,946 $ 203,190 $ 94,946 $ 203,190