Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	3 Months Ended								9 Months Ended
	Sep. 30, 2020 USD ($) oz		Jun. 30, 2020 USD ($) oz	Mar. 31, 2020 USD ($) oz		Sep. 30, 2019 USD ($) oz	Jun. 30, 2019 USD ($) oz	Mar. 31, 2019 USD ($) oz	Sep. 30, 2020 USD ($) oz		Sep. 30, 2019 USD ($) oz
Beginning balance (Ounce) | oz	14,658,518			11,577,252		9,474,090		9,009,541	11,577,252		9,009,541
Beginning balance, average cost	$ 20,470,354,346			$ 15,094,673,874		$ 11,930,367,963		$ 11,255,129,376	$ 15,094,673,874		$ 11,255,129,376
Beginning balance, fair value	$ 25,917,726,586			17,632,155,037	[1]	$ 13,348,992,576		11,547,078,166	$ 17,632,155,037	[1]	$ 11,547,078,166
Gold bullion contributed (Ounce) | oz	2,187,720					1,625,180			6,096,339		2,990,628
Gold bullion contributed, average cost	$ 4,165,602,762					$ 2,411,110,878			$ 10,646,693,556		$ 4,215,794,689
Gold bullion contributed, fair value	$ 4,165,602,762					$ 2,411,110,878			$ 10,646,693,556		$ 4,215,794,689
Gold bullion distributed (Ounce) | oz	(176,520)					(81,313)			(988,456)		(970,668)
Gold bullion distributed, average cost	$ (254,187,327)					$ (103,411,024)			$ (1,338,913,068)		$ (1,218,395,838)
Gold bullion distributed, fair value	(327,658,445)					(120,691,118)			(1,618,156,723)		(1,263,373,084)
Gold bullion distributed, realized gain (loss)	$ 73,471,118					$ 17,280,094			$ 279,243,655		$ 44,977,246
Gold bullion sold to pay expenses (Ounce) | oz	(9,260)					(5,970)			(24,677)		(17,514)
Gold bullion sold to pay expenses, average cost	$ (13,240,877)					$ (7,578,716)			$ (33,925,458)		$ (22,039,126)
Gold bullion sold to pay expenses, fair value	(17,644,516)					(8,641,399)			(42,623,290)		(23,662,396)
Gold bullion sold to pay expenses, realized gain (loss)	4,403,639					1,062,683			8,697,832		1,623,270
Net realized gain (loss), fair value	77,874,757		$ 58,420,248	151,646,482		18,342,777	$ 22,410,307	5,847,432	287,941,487		46,600,516
Net change in unrealized appreciation/depreciation, fair value	$ 1,620,716,613		$ 2,078,877,217	831,013,860		$ 706,990,277	$ 1,012,499,328	114,176,495	$ 4,530,607,690		$ 1,833,666,100
Ending balance (Ounce) | oz	16,660,458		14,658,518			11,011,987	9,474,090		16,660,458		11,011,987
Ending balance, average cost	$ 24,368,528,904		$ 20,470,354,346			$ 14,230,489,101	$ 11,930,367,963		$ 24,368,528,904		$ 14,230,489,101
Ending balance, fair value	31,436,617,757	[1]	25,917,726,586			16,356,103,991	13,348,992,576		31,436,617,757	[1]	16,356,103,991
Ending balance, realized gain (loss)	$ 77,874,757		$ 58,420,248	$ 151,646,482		$ 18,342,777	$ 22,410,307	$ 5,847,432	$ 287,941,487		$ 46,600,516

[1] Cost of investment in gold bullion: $24,368,528,904 and $15,094,673,874, respectively.