Summary Of Significant Accounting Policies (Activity In Gold Bullion) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012 Ounce	Jun. 30, 2011	Jun. 30, 2012 Ounce	Jun. 30, 2011
Summary Activity In Gold Bullion [Line Items]
Beginning balance, Ounces	5,813,100		5,498,800
Gold contributed, Ounces	230,800		598,300
Gold distributed, Ounces	(221,100)		(270,800)
Gold sold, Ounces	(3,600)		(7,100)
Ending balance, Ounces	5,819,200		5,819,200
Beginning balance, Average Cost	$ 7,137,395		$ 6,572,102
Gold contributed, Average Cost	368,304		998,830
Gold distributed, Average Cost	(272,307)		(333,325)
Gold sold, Average Cost	(4,447)		(8,662)
Ending balance, Average Cost	7,228,945		7,228,945
Beginning balance, Fair Value	9,664,400		8,418,739
Gold contributed, Fair Value	368,304		998,830
Gold distributed, Fair Value	(348,173)		(430,539)
Gold sold, Fair Value	(5,973)		(11,824)
Adjustment for realized gain, Fair Value	77,392		100,376
Adjustment for unrealized gain (loss), Fair Value	(453,856)		226,512
Ending balance, Fair Value	9,302,094		9,302,094
Gold distributed, Realized Gain (Loss)	75,866		97,214
Gold sold, Realized Gain (Loss)	1,526	1,209	3,162	2,165
Ending balance, Realized Gain (Loss)	$ 77,392		$ 100,376