Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	3 Months Ended			12 Months Ended
	Mar. 31, 2018 USD ($) oz		Mar. 31, 2017 USD ($) oz	Dec. 31, 2017 USD ($) oz
Beginning balance (Ounce) | oz	7,828,465		6,308,062	6,308,062
Gold bullion contributed (Ounce) | oz	930,477		355,672
Gold bullion distributed (Ounce) | oz	(28,802)		(234,367)
Gold bullion sold to pay expenses (Ounce) | oz	(4,950)		(3,907)
Ending balance (Ounce) | oz	8,725,190		6,425,460	7,828,465
Beginning balance, average cost	$ 9,663,574,842		$ 7,706,923,343	$ 7,706,923,343
Gold bullion contributed, average cost	1,237,667,439		431,456,784
Gold bullion distributed, average cost	(35,797,403)		(286,185,422)
Gold bullion sold to pay expenses, average cost	(6,136,226)		(4,771,262)
Ending balance, average cost	10,859,308,652		7,847,423,443	9,663,574,842
Beginning balance, fair value	10,149,604,427	[1]	7,311,674,849	7,311,674,849
Gold bullion contributed, fair value	1,237,667,439		431,456,784
Gold bullion distributed, fair value	(37,957,322)		(288,297,575)
Gold bullion sold to pay expenses, fair value	(6,537,373)		(4,677,360)
Net realized gain (loss), fair value	2,561,066		2,018,251	22,215,914
Net change in unrealized appreciation/depreciation, fair value	205,503,998		546,559,551	881,278,079
Ending balance, fair value	11,550,842,235	[1]	7,998,734,500	10,149,604,427	[1]
Gold bullion distributed, realized gain (loss)	2,159,919		2,112,153
Gold bullion sold to pay expenses, realized gain (loss)	401,147		(93,902)
Ending balance, realized gain (loss)	$ 2,561,066		$ 2,018,251	$ 22,215,914

[1] Cost of investment in gold bullion: $10,859,308,652 and $9,663,574,842, respectively.