Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) oz		Dec. 31, 2018 USD ($) oz		Dec. 31, 2017 USD ($) oz
Beginning balance (Ounce) | oz	9,009,541		7,828,465		6,308,062
Beginning balance, average cost	$ 11,255,129,376		$ 9,663,574,842		$ 7,706,923,343
Beginning balance, fair value	$ 11,547,078,166	[1]	$ 10,149,604,427		$ 7,311,674,849
Gold bullion contributed (Ounce) | oz	3,668,032		2,370,108		2,194,645
Gold bullion contributed, average cost	$ 5,226,042,788		$ 3,078,649,161		$ 2,782,113,163
Gold bullion contributed, fair value	$ 5,226,042,788		$ 3,078,649,161		$ 2,782,113,163
Gold bullion distributed (Ounce) | oz	(1,075,809)		(1,167,483)		(657,409)
Gold bullion distributed, average cost	$ (1,355,372,636)		$ (1,460,213,703)		$ (804,830,293)
Gold bullion distributed, fair value	(1,418,257,979)		(1,483,295,672)		(826,600,408)
Gold bullion distributed, realized gain (loss)	$ 62,885,343		$ 23,081,969		$ 21,770,115
Gold bullion sold to pay expenses (Ounce) | oz	(24,512)		(21,549)		(16,833)
Gold bullion sold to pay expenses, average cost	$ (31,125,654)		$ (26,880,924)		$ (20,631,371)
Gold bullion sold to pay expenses, fair value	(34,028,445)		(27,290,381)		(21,077,170)
Gold bullion sold to pay expenses, realized gain (loss)	2,902,791		409,457		445,799
Net realized gain (loss), fair value	65,788,134		23,491,426		22,215,914
Net change in unrealized appreciation/depreciation, fair value	$ 2,245,532,373		$ (194,080,795)		$ 881,278,079
Ending balance (Ounce) | oz	11,577,252		9,009,541		7,828,465
Ending balance, average cost	$ 15,094,673,874		$ 11,255,129,376		$ 9,663,574,842
Ending balance, fair value	17,632,155,037	[1]	11,547,078,166	[1]	10,149,604,427
Ending balance, realized gain (loss)	$ 65,788,134		$ 23,491,426		$ 22,215,914

[1] Cost of investment in gold bullion: $15,094,673,874 and $11,255,129,376, respectively.