Fair Value of ETC - Summary of changes in quantity of ETC and the respective fair value (Detail) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2025 USD ($) ETC	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($) ETC	Dec. 31, 2024 USD ($) ETC	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($) ETC	Dec. 31, 2025 USD ($) ETC	Dec. 31, 2024 USD ($) ETC	Dec. 31, 2023 USD ($) ETC
Fair Value Disclosures [Abstract]
Investment Owned, Balance \| ETC				11,263,626.2550315				11,548,776.1723	11,263,626.2550315	11,548,776.1723	11,841,144.97143656
ETC contributed \| ETC									0	0	0
ETC distributed for Sponsor's Fee, related party \| ETC									(278,109.32895859)	(285,149.91726843)	(292,368.79913656)
Net change in unrealized (depreciation) appreciation on investment in ETC \| ETC									0	0	0
Net realized gain on investment in ETC \| ETC									0	0	0
Investment Owned, Balance \| ETC	10,985,516.92607291				11,263,626.2550315				10,985,516.92607291	11,263,626.2550315	11,548,776.1723
Investment Owned, at Fair Value \| $				$ 283,055				$ 253,958	$ 283,055	$ 253,958	$ 187,327
ETC contributed \| $									0	0	0
ETC distributed for Sponsor's Fee, related party \| $									(5,161)	(7,157)	(5,476)
Net change in unrealized appreciation (depreciation) on investment in ETC \| $	$ (76,662)	$ 17,154	$ (1,424)	(94,019)	$ 60,640	$ (45,236)	$ (121,879)	137,726	(154,951)	31,251	68,838
Net realized gain (loss) on investment in ETC \| $	507	$ 912	$ 653	$ 989	1,221	$ 896	$ 1,436	$ 1,450	3,061	5,003	3,269
Investment Owned, at Fair Value \| $	$ 126,004				$ 283,055				$ 126,004	$ 283,055	$ 253,958