Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	3 Months Ended			6 Months Ended			12 Months Ended
	Jun. 30, 2018 USD ($) oz		Jun. 30, 2017 USD ($) oz	Jun. 30, 2018 USD ($) oz		Jun. 30, 2017 USD ($) oz	Dec. 31, 2017 USD ($) oz
Beginning balance (Ounce) | oz	8,725,190		6,425,460	7,828,465		6,308,062	6,308,062
Gold bullion contributed (Ounce) | oz	689,115		450,189	1,619,592		805,861
Gold bullion distributed (Ounce) | oz	(770,898)		(108,710)	(799,700)		(343,077)
Gold bullion sold to pay expenses (Ounce) | oz	(5,705)		(4,047)	(10,655)		(7,954)
Ending balance (Ounce) | oz	8,637,702		6,762,892	8,637,702		6,762,892	7,828,465
Beginning balance, average cost	$ 10,859,308,652		$ 7,847,423,443	$ 9,663,574,842		$ 7,706,923,343	$ 7,706,923,343
Gold bullion contributed, average cost	918,575,987		568,086,499	2,156,243,426		999,543,283
Gold bullion distributed, average cost	(964,441,439)		(132,886,400)	(1,000,238,842)		(419,071,822)
Gold bullion sold to pay expenses, average cost	(7,126,305)		(4,946,225)	(13,262,531)		(9,717,487)
Ending balance, average cost	10,806,316,895		8,277,677,317	10,806,316,895		8,277,677,317	9,663,574,842
Beginning balance, fair value	11,550,842,235		7,998,734,500	10,149,604,427	[1]	7,311,674,849	7,311,674,849
Gold bullion contributed, fair value	918,575,987		568,086,499	2,156,243,426		999,543,283
Gold bullion distributed, fair value	(992,947,997)		(135,318,870)	(1,030,905,319)		(423,616,445)
Gold bullion sold to pay expenses, fair value	(7,479,964)		(5,082,699)	(14,017,337)		(9,760,059)
Net realized gain (loss), fair value	28,860,217		2,568,944	31,421,283		4,587,195	22,215,914
Net change in unrealized appreciation/depreciation, fair value	(696,835,646)		(27,785,695)	(491,331,648)		518,773,856	881,278,079
Ending balance, fair value	10,801,014,832	[1]	8,401,202,679	10,801,014,832	[1]	8,401,202,679	10,149,604,427	[1]
Gold bullion distributed, realized gain (loss)	28,506,558		2,432,470	30,666,477		4,544,623
Gold bullion sold to pay expenses, realized gain (loss)	353,659		136,474	754,806		42,572
Ending balance, realized gain (loss)	$ 28,860,217		$ 2,568,944	$ 31,421,283		$ 4,587,195	$ 22,215,914

[1] Cost of investment in gold bullion: $10,806,316,895 and $9,663,574,842, respectively.