Note 2 - Significant Accounting Policies - Activity in Silver Bullion (Details)	3 Months Ended						6 Months Ended
	Jun. 30, 2024 USD ($) oz		Mar. 31, 2024 USD ($) oz		Jun. 30, 2023 USD ($) oz	Mar. 31, 2023 USD ($) oz	Jun. 30, 2024 USD ($) oz		Jun. 30, 2023 USD ($) oz
Beginning balance (Ounce) | oz	430,806,891		436,892,231		463,942,222	466,265,146	436,892,231		466,265,146
Beginning balance, average cost	$ 9,568,548,144		$ 9,616,427,847		$ 10,057,834,978	$ 10,025,562,224	$ 9,616,427,847		$ 10,025,562,224
Beginning balance, fair value	$ 10,572,001,097		10,393,666,180	[1]	$ 11,081,259,981	11,164,718,926	$ 10,393,666,180	[1]	$ 11,164,718,926
Silver bullion contributed (Ounce) | oz	73,975,988				35,590,738		129,646,899		92,652,599
Silver bullion contributed, average cost	$ 2,115,572,235				$ 868,097,632		$ 3,430,050,047		$ 2,184,456,395
Silver bullion contributed, fair value	$ 2,115,572,235				$ 868,097,632		$ 3,430,050,047		$ 2,184,456,395
Silver bullion distributed (Ounce) | oz	(66,811,439)				(30,812,468)		(128,019,703)		(89,610,880)
Silver bullion distributed, average cost	$ (1,508,108,680)				$ (671,788,422)		$ (2,858,390,089)		$ (1,943,206,955)
Silver bullion distributed, fair value	(1,921,737,558)				(751,430,827)		(3,354,168,770)		(2,072,026,634)
Silver bullion distributed, realized gain (loss)	$ 413,628,878				$ 79,642,405		$ 495,778,681		$ 128,819,679
Silver bullion sold to pay expenses (Ounce) | oz	(523,574)				(579,393)		(1,071,561)		(1,165,766)
Silver bullion sold to pay expenses, average cost	$ (11,788,913)				$ (12,617,472)		$ (23,865,019)		$ (25,284,948)
Silver bullion sold to pay expenses, fair value	(14,386,475)				(13,936,229)		(27,056,987)		(27,379,746)
Silver bullion sold to pay expenses, realized gain (loss)	2,597,562				1,318,757		3,191,968		2,094,798
Net realized gain (loss), fair value	416,226,440		82,744,209		80,961,162	49,953,315	498,970,649		130,914,477
Net change in unrealized appreciation/depreciation, fair value	$ 1,680,168,086		$ 226,214,620		$ (745,821,212)	$ (115,731,699)	$ 1,906,382,706		$ (861,552,911)
Ending balance (Ounce) | oz	437,447,866		430,806,891		468,141,099	463,942,222	437,447,866		468,141,099
Ending balance, average cost	$ 10,164,222,786		$ 9,568,548,144		$ 10,241,526,716	$ 10,057,834,978	$ 10,164,222,786		$ 10,241,526,716
Ending balance, fair value	12,847,843,825	[1]	10,572,001,097		10,519,130,507	11,081,259,981	12,847,843,825	[1]	10,519,130,507
Ending balance, realized gain (loss)	$ 416,226,440		$ 82,744,209		$ 80,961,162	$ 49,953,315	$ 498,970,649		$ 130,914,477

[1] Cost of investment in silver bullion: $10,164,222,786 and $9,616,427,847, respectively.