INVESTMENT IN BITCOIN - Changes in Quantity of Bitcoin Held (Details) - Franklin Bitcoin ETF [Member]	3 Months Ended			9 Months Ended
	Dec. 31, 2025 USD ($) Bitcoin		Dec. 31, 2024 USD ($) Bitcoin	Dec. 31, 2025 USD ($) Bitcoin		Dec. 31, 2024 USD ($) Bitcoin
INVESTMENT IN BITCOIN [Abstract]
Beginning balance (in Bitcoin) | Bitcoin	5,789.9639		7,103.8488	4,956.3464		4,842.9986
Beginning balance of fair value	$ 661,347,104		$ 452,356,258	$ 411,158,674	[1]	$ 341,901,126
Bitcoin purchased for the creation of Shares, Quantity (in Bitcoin) | Bitcoin	289.3033		869.5836	1,707.8385		4,262.4171
Bitcoin purchased for the creation of Shares	$ 28,966,925		$ 69,053,710	$ 177,354,133		$ 278,780,084
Bitcoin sold for the redemption of Shares, Quantity (in Bitcoin) | Bitcoin	(347.1368)		(347.8288)	(926.2185)		(1,478.7943)
Bitcoin sold for the redemption of Shares	$ (32,029,773)		$ (23,658,861)	$ (86,635,022)		$ (89,377,452)
Principal on bitcoin sales to pay expenses, Quantity (in Bitcoin) | Bitcoin	(4.4775)		(1.0863)	(10.3135)		(2.1041)
Principal on bitcoin sales to pay expenses	$ (491,472)		$ (65,679)	$ (1,030,146)		$ (123,368)
Net realized gain (loss) from bitcoin sold for the redemption of shares and sold to pay expenses	6,465,881		2,814,719	22,776,065		1,657,725
Net change in unrealized appreciation (depreciation) on investment in bitcoin	$ (163,300,788)		$ 211,365,660	$ (22,665,827)		$ 179,027,692
Ending balance (in Bitcoin) | Bitcoin	5,727.6529		7,624.5173	5,727.6529		7,624.5173
Ending balance of fair value	$ 500,957,877	[1]	$ 711,865,807	$ 500,957,877	[1]	$ 711,865,807

[1] Cost of investment in bitcoin: $426,448,438 at December 31, 2025 and $313,983,408 at March 31, 2025.