Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	3 Months Ended						6 Months Ended
	Jun. 30, 2020 USD ($) oz		Mar. 31, 2020 USD ($) oz		Jun. 30, 2019 USD ($) oz	Mar. 31, 2019 USD ($) oz	Jun. 30, 2020 USD ($) oz		Jun. 30, 2019 USD ($) oz
Beginning balance (Ounce) | oz	12,571,766		11,577,252		9,695,079	9,009,541	11,577,252		9,009,541
Beginning balance, average cost	$ 16,858,848,412		$ 15,094,673,874		$ 12,152,880,181	$ 11,255,129,376	$ 15,094,673,874		$ 11,255,129,376
Beginning balance, fair value	$ 20,227,343,435		17,632,155,037	[1]	$ 12,559,005,466	11,547,078,166	$ 17,632,155,037	[1]	$ 11,547,078,166
Gold bullion contributed (Ounce) | oz	2,271,113				546,477		3,908,619		1,365,448
Gold bullion contributed, average cost	$ 3,865,881,490				$ 739,781,522		$ 6,481,090,794		$ 1,804,683,811
Gold bullion contributed, fair value	$ 3,865,881,490				$ 739,781,522		$ 6,481,090,794		$ 1,804,683,811
Gold bullion distributed (Ounce) | oz	(176,145)				(761,506)		(811,936)		(889,355)
Gold bullion distributed, average cost	$ (243,162,746)				$ (954,820,867)		$ (1,084,725,741)		$ (1,114,984,814)
Gold bullion distributed, fair value	(299,101,991)				(976,968,626)		(1,290,498,278)		(1,142,681,966)
Gold bullion distributed, realized gain (loss)	$ 55,939,245				$ 22,147,759		$ 205,772,537		$ 27,697,152
Gold bullion sold to pay expenses (Ounce) | oz	(8,216)				(5,960)		(15,417)		(11,544)
Gold bullion sold to pay expenses, average cost	$ (11,212,810)				$ (7,472,873)		$ (20,684,581)		$ (14,460,410)
Gold bullion sold to pay expenses, fair value	(13,693,813)				(7,735,421)		(24,978,774)		(15,020,997)
Gold bullion sold to pay expenses, realized gain (loss)	2,481,003				262,548		4,294,193		560,587
Net realized gain (loss), fair value	58,420,248		151,646,482		22,410,307	5,847,432	210,066,730		28,257,739
Net change in unrealized appreciation/depreciation, fair value	$ 2,078,877,217		$ 831,013,860		$ 1,012,499,328	$ 114,176,495	$ 2,909,891,077		$ 1,126,675,823
Ending balance (Ounce) | oz	14,658,518		12,571,766		9,474,090	9,695,079	14,658,518		9,474,090
Ending balance, average cost	$ 20,470,354,346		$ 16,858,848,412		$ 11,930,367,963	$ 12,152,880,181	$ 20,470,354,346		$ 11,930,367,963
Ending balance, fair value	25,917,726,586	[1]	20,227,343,435		13,348,992,576	12,559,005,466	25,917,726,586	[1]	13,348,992,576
Ending balance, realized gain (loss)	$ 58,420,248		$ 151,646,482		$ 22,410,307	$ 5,847,432	$ 210,066,730		$ 28,257,739

[1] Cost of investment in gold bullion: $20,470,354,346 and $15,094,673,874, respectively.