Combined Statements of Assets and Liabilities (Parentheticals) - USD ($)	6 Months Ended	12 Months Ended
	Sep. 30, 2025	Mar. 31, 2025
Investment in bitcoin, at cost	$ 423,536,877	$ 313,983,408
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized, unlimited	Unlimited	Unlimited
Franklin Bitcoin ETF [Member]
Investment in bitcoin, at cost	$ 423,536,877	$ 313,983,408
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized, unlimited	Unlimited	Unlimited