Combined Schedules of Investments		Sep. 30, 2025 USD ($) Bitcoin	Mar. 31, 2025 USD ($) Bitcoin
Combined Schedule of Investments [Abstract]
Quantity of Bitcoin (in Bitcoin) | Bitcoin		5,789.9639	4,956.3464
Total investments, Cost		$ 423,536,877	$ 313,983,408
Total investments, Fair Value	[1]	$ 661,347,104	$ 411,158,674
Total investments, Fair Value as a % of Net Assets		100.04%	100.07%
Less liabilities, Fair Value		$ (296,639)	$ (301,331)
Less liabilities, Fair Value as a % of Net Assets		(0.04%)	(0.07%)
Net assets		$ 661,050,465	$ 410,857,343
Net assets, Fair Value as a % of Net Assets		100.00%	100.00%
Franklin Bitcoin ETF [Member]
Combined Schedule of Investments [Abstract]
Quantity of Bitcoin (in Bitcoin) | Bitcoin		5,789.9639	4,956.3464
Total investments, Cost		$ 423,536,877	$ 313,983,408
Total investments, Fair Value	[1]	$ 661,347,104	$ 411,158,674
Total investments, Fair Value as a % of Net Assets		100.04%	100.07%
Less liabilities, Fair Value		$ (296,639)	$ (301,331)
Less liabilities, Fair Value as a % of Net Assets		(0.04%)	(0.07%)
Net assets		$ 661,050,465	$ 410,857,343
Net assets, Fair Value as a % of Net Assets		100.00%	100.00%
Bitcoin [Member]
Combined Schedule of Investments [Abstract]
Quantity of Bitcoin (in Bitcoin) | Bitcoin		5,789.9639	4,956.3464
Total investments, Cost		$ 423,536,877	$ 313,983,408
Total investments, Fair Value		$ 661,347,104	$ 411,158,674
Total investments, Fair Value as a % of Net Assets		100.04%	100.07%
Bitcoin [Member] | Franklin Bitcoin ETF [Member]
Combined Schedule of Investments [Abstract]
Quantity of Bitcoin (in Bitcoin) | Bitcoin		5,789.9639	4,956.3464
Total investments, Cost		$ 423,536,877	$ 313,983,408
Total investments, Fair Value		$ 661,347,104	$ 411,158,674
Total investments, Fair Value as a % of Net Assets		100.04%	100.07%

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