Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) oz		Mar. 31, 2019 USD ($) oz
Beginning balance (Ounce) | oz	11,577,252		9,009,541
Beginning balance, average cost	$ 15,094,673,874		$ 11,255,129,376
Beginning balance, fair value	$ 17,632,155,037	[1]	$ 11,547,078,166
Gold bullion contributed (Ounce) | oz	1,637,506		818,971
Gold bullion contributed, average cost	$ 2,615,209,304		$ 1,064,902,289
Gold bullion contributed, fair value	$ 2,615,209,304		$ 1,064,902,289
Gold bullion distributed (Ounce) | oz	(635,791)		(127,849)
Gold bullion distributed, average cost	$ (841,562,995)		$ (160,163,947)
Gold bullion distributed, fair value	(991,396,287)		(165,713,340)
Gold bullion distributed, realized gain (loss)	$ 149,833,292		$ 5,549,393
Gold bullion sold to pay expenses (Ounce) | oz	(7,201)		(5,584)
Gold bullion sold to pay expenses, average cost	$ (9,471,771)		$ (6,987,537)
Gold bullion sold to pay expenses, fair value	(11,284,961)		(7,285,576)
Gold bullion sold to pay expenses, realized gain (loss)	1,813,190		298,039
Net realized gain (loss), fair value	151,646,482		5,847,432
Net change in unrealized appreciation/depreciation, fair value	$ 831,013,860		$ 114,176,495
Ending balance (Ounce) | oz	12,571,766		9,695,079
Ending balance, average cost	$ 16,858,848,412		$ 12,152,880,181
Ending balance, fair value	20,227,343,435	[1]	12,559,005,466
Ending balance, realized gain (loss)	$ 151,646,482		$ 5,847,432

[1] Cost of investment in gold bullion: $16,858,848,412 and $15,094,673,874, respectively.