INVESTMENT IN BITCOIN - Changes in Quantity of Bitcoin Held (Details) - Franklin Bitcoin ETF [Member]	3 Months Ended			6 Months Ended
	Sep. 30, 2025 USD ($) Bitcoin		Sep. 30, 2024 USD ($) Bitcoin	Sep. 30, 2025 USD ($) Bitcoin		Sep. 30, 2024 USD ($) Bitcoin
INVESTMENT IN BITCOIN [Abstract]
Beginning balance (in Bitcoin) | Bitcoin	5,155.3659		5,886.9982	4,956.3464		4,842.9986
Beginning balance of fair value	$ 559,666,521		$ 373,054,955	$ 411,158,674	[1]	$ 341,901,126
Bitcoin purchased for the creation of Shares, Quantity (in Bitcoin) | Bitcoin	810.3845		1,768.8331	1,418.5352		3,392.8311
Bitcoin purchased for the creation of Shares	$ 92,885,565		$ 107,983,297	$ 148,387,208		$ 209,726,374
Bitcoin sold for the redemption of Shares, Quantity (in Bitcoin) | Bitcoin	(173.6506)		(550.9655)	(579.0817)		(1,130.9639)
Bitcoin sold for the redemption of Shares	$ (19,374,669)		$ (31,419,621)	$ (54,605,249)		$ (65,718,591)
Principal on bitcoin sales to pay expenses, Quantity (in Bitcoin) | Bitcoin	(2.1359)		(1.017)	(5.836)		(1.017)
Principal on bitcoin sales to pay expenses	$ (237,340)		$ (57,689)	$ (538,674)		$ (57,689)
Net realized gain (loss) from bitcoin sold for the redemption of shares and sold to pay expenses	7,290,973		(1,325,741)	16,310,184		(1,156,994)
Net change in unrealized appreciation (depreciation) on investment in bitcoin	$ 21,116,054		$ 4,121,057	$ 140,634,961		$ (32,337,968)
Ending balance (in Bitcoin) | Bitcoin	5,789.9639		7,103.8488	5,789.9639		7,103.8488
Ending balance of fair value	$ 661,347,104	[1]	$ 452,356,258	$ 661,347,104	[1]	$ 452,356,258

[1] Cost of investment in bitcoin: $423,536,877 at September 30, 2025 and $313,983,408 at March 31, 2025.