Note 2 - Summary of Significant Accounting Policies (Details) - Activity in Silver Bullion (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 oz		Dec. 31, 2013 oz		Dec. 31, 2012 oz
Activity in Silver Bullion [Abstract]
Beginning balance (in Ounces)	320,177,800		324,239,100		308,833,300
Beginning balance	$ 6,243,467
Beginning balance	6,243,467
Silver bullion contributed (in Ounces)	71,956,100		82,810,600		79,657,000
Silver bullion contributed, average cost	1,361,917		2,096,484		2,496,406
Silver contributed, fair value	1,361,917		2,096,484		2,496,406
Silver distributed (in Ounces)	(60,878,000)		(85,164,100)		(62,700,400)
Silver distributed, average cost	(1,185,617)		(2,163,458)		(1,515,494)
Silver distributed, fair value	(1,108,223)		(2,031,644)		(1,943,269)
Silver distributed, realized gain (loss)			(131,814)		427,775
Silver bullion distributed (in Ounces)	(60,878,000)		(85,164,100)		(62,700,400)
Silver bullion distributed	(1,185,617)		(2,163,458)		(1,515,494)
Silver bullion distributed	(1,108,223)		(2,031,644)		(1,943,269)
Silver bullion distributed	(77,394)	[1]	(131,814)		427,775
Silver bullion sold (in Ounces)	(1,691,700)		(1,707,800)		(1,550,800)
Silver bullion sold, average cost	(33,017)		(43,296)		(37,369)
Silver sold, fair value	(31,961)		(41,406)		(48,390)
Silver sold, realized gain (loss)	(1,056)	[1]	(1,890)		11,021
Adjustment to silver bullion inventory(a)			(1,781,266)	[2]
Adjustment for realized gain (loss)			(133,704)		438,796
Adjustment for unrealized gain (loss) on silver bullion			(3,357,225)		64,497
Ending balance (in Ounces)	329,564,200	[3]	320,177,800		324,239,100
Ending balance, average cost			6,243,467		8,135,003
Ending balance, fair value			6,243,467		9,710,962
Ending balance, realized gain (loss)			(133,704)		438,796
Net realized loss on silver bullion	(78,450)
Net change in unrealized appreciation/depreciation on investment in silver bullion	(1,123,610)	[1]
Ending balance	6,386,750	[3]	6,243,467
Ending balance	5,263,140	[3],[4]	6,243,467
Ending balance	(78,450)
Beginning balance, average cost	6,243,467		8,135,003		7,191,460
Beginning balance, fair value	$ 6,243,467		$ 9,710,962		$ 8,702,922

[1] Effective January 1, 2014, the Trust qualifies as an investment company for accounting purposes. Please refer to Note 2B.

[2] At December 31, 2013, the market value of the silver bullion was below the average cost of the Trust's silver bullion inventory held. As a result, the Trust recorded a permanent write down against the average cost of the silver bullion inventory of $1,781,266.

[3] Effective January 1, 2014, the Trust qualifies as an investment company for accounting purposes. Disclosure of a schedule of investments is required for investment companies. Please refer to Note 2B.

[4] Presented at fair value at December 31, 2014 (cost: $6,386,750).