Summary Of Significant Accounting Policies (Activity In Silver Bullion) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2009		Dec. 31, 2008
Summary Of Significant Accounting Policies [Abstract]
Beginning balance, Ounces	305,206,000	218,399,700		150,801,200
Silver contributed, Ounces	87,675,400	108,877,600		93,510,300
Silver distributed, Ounces	(40,268,300)	(20,775,600)		(24,955,700)
Silver sold, Ounces	(1,476,300)	(1,295,700)		(956,100)
Ending balance, Ounces	351,136,800	305,206,000		218,399,700
Beginning balance, Average Cost	$ 4,210,142	$ 2,928,317	[1]	$ 1,838,497
Silver contributed, Average Cost	2,040,507	1,575,673		1,438,131
Silver distributed, Average Cost	(579,557)	(276,552)		(335,617)
Silver sold, Average Cost	(20,954)	(17,296)		(12,694)
Ending balance, Average Cost	5,650,138	4,210,142		2,928,317	[1]
Beginning balance, Fair Value	5,185,449	2,356,533		2,225,826
Silver contributed, Fair Value	2,040,507	1,575,673		1,438,131
Silver distributed, Fair Value	(836,960)	(297,947)		(316,791)
Silver sold, Fair Value	(29,257)	(18,718)		(14,313)
Adjustment for realized gain, Fair Value	265,706	22,817		(17,207)
Adjustment for unrealized gain on silver bullion, Fair Value	4,129,874	1,547,091		(959,113)
Ending balance, Fair Value	10,755,319	5,185,449		2,356,533
Silver distributed, Realized Gain (Loss)	257,403	21,395		(18,826)
Silver sold, Realized Gain (Loss)	8,303	1,422		1,619
Ending balance, Realized Gain (Loss)	$ 265,706	$ 22,817		$ (17,207)

[1] Refer to Note 1A for a discussion of the restatement.