Note 2 - Significant Accounting Policies (Details) - Activity in Silver Bullion $ in Thousands		12 Months Ended
		Dec. 31, 2015 USD ($) oz		Dec. 31, 2014 USD ($) oz		Dec. 31, 2013 USD ($) oz
Activity in Silver Bullion [Abstract]
Beginning balance (in Ounces) | oz		329,564,200		320,177,800		324,239,100
Beginning balance, average cost		$ 6,386,750		$ 6,243,467		$ 8,135,003
Beginning balance, fair value		$ 5,263,140	[1]	$ 6,243,467		$ 9,710,962
Silver bullion contributed (in Ounces) | oz		54,595,700		71,956,100		82,810,600
Silver bullion contributed, average cost		$ 859,468		$ 1,361,917		$ 2,096,484
Silver bullion contributed, fair value		$ 859,468		$ 1,361,917		$ 2,096,484
Silver bullion distributed (in Ounces) | oz		(64,583,500)		(60,878,000)		(85,164,100)
Silver bullion distributed		$ (1,235,547)		$ (1,185,617)		$ (2,163,458)
Silver bullion distributed		$ (1,029,094)		$ (1,108,223)		(2,031,644)
Silver bullion distributed						$ (131,814)
Silver bullion sold (in Ounces) | oz		(1,641,500)		(1,691,700)		(1,707,800)
Silver bullion sold		$ (31,419)		$ (33,017)		$ (43,296)
Silver bullion sold		$ (25,716)		$ (31,961)		(41,406)
Silver bullion sold						(1,890)
Adjustment to silver bullion inventory(a)	[2]					(1,781,266)
Adjustment for realized loss on silver bullion						(133,704)
Adjustment for unrealized loss on silver bullion						$ (3,357,225)
Ending balance (in Ounces) | oz		317,934,900		329,564,200		320,177,800
Ending balance		$ 5,979,252		$ 6,386,750		$ 6,243,467
Ending balance		4,393,861	[1]	5,263,140	[1]	6,243,467
Ending balance						(133,704)
Silver bullion distributed, average cost		(1,235,547)		(1,185,617)		(2,163,458)
Silver bullion distributed, fair value		(1,029,094)		(1,108,223)		(2,031,644)
Silver bullion distributed, realized gain (loss)		$ (206,453)	[3]	$ (77,394)	[3]	$ (131,814)
Silver bullion sold to pay expenses (in Ounces) | oz		(1,641,500)		(1,691,700)		(1,707,800)
Silver bullion sold to pay expenses, average cost		$ (31,419)		$ (33,017)		$ (43,296)
Silver bullion sold to pay expenses, fair value		(25,716)		(31,961)		(41,406)
Silver bullion sold to pay expenses, realized gain (loss)	[3]	(5,703)		(1,056)
Net realized gain (loss)	[3]	(212,156)		(78,450)
Net change in unrealized appreciation/depreciation	[3]	(461,781)		(1,123,610)
Ending balance, average cost		5,979,252		6,386,750		6,243,467
Ending balance, fair value		4,393,861	[1]	5,263,140	[1]	$ 6,243,467
Ending balance, realized gain (loss)	[3]	$ (212,156)		$ (78,450)

[1] Cost of investment in silver bullion: $5,979,252 and $6,386,750, respectively.

[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, theTrust 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 qualified as an investment company for accounting purposes. Please refer to Note 2B.