Note 2 - Significant Accounting Policies - Activity in Gold Bullion (Details)	3 Months Ended			12 Months Ended
	Mar. 31, 2017 USD ($) oz		Mar. 31, 2016 USD ($) oz	Dec. 31, 2016 USD ($) oz
Beginning balance (Ounce) | oz	6,308,062		4,905,568	4,905,568
Beginning balance, average cost	$ 7,706,923,343		$ 5,910,175,908	$ 5,910,175,908
Beginning balance, fair value	$ 7,311,674,849	[1]	$ 5,210,940,144	5,210,940,144
Gold bullion contributed (Ounce) | oz	355,672		1,360,213
Gold bullion contributed, average cost	$ 431,456,784		$ 1,593,830,000
Gold bullion contributed, fair value	$ 431,456,784		$ 1,593,830,000
Gold bullion distributed (Ounce) | oz	(234,367)		(272,052)
Gold bullion distributed, average cost	$ (286,185,422)		$ (325,745,016)
Gold bullion distributed, fair value	(288,297,575)		(332,909,854)
Gold bullion distributed, realized gain (loss)	$ 2,112,153		$ 7,164,838
Gold bullion sold to pay expenses (Ounce) | oz	(3,907)		(3,214)
Gold bullion sold to pay expenses, average cost	$ (4,771,262)		$ (3,853,659)
Gold bullion sold to pay expenses, fair value	(4,677,360)		(3,695,797)
Gold bullion sold to pay expenses, realized gain (loss)	(93,902)		(157,862)
Net realized gain (loss), fair value	2,018,251		7,006,976	25,068,804
Net change in unrealized appreciation/depreciation, fair value	$ 546,559,551		$ 935,095,915	$ 303,987,270
Ending balance (Ounce) | oz	6,425,460		5,990,515	6,308,062
Ending balance, average cost	$ 7,847,423,443		$ 7,174,407,233	$ 7,706,923,343
Ending balance, fair value	7,998,734,500	[1]	7,410,267,384	7,311,674,849	[1]
Ending balance, realized gain (loss)	$ 2,018,251		$ 7,006,976	$ 25,068,804

[1] Cost of investment in gold bullion: $7,847,423,443 and $7,706,923,343, respectively.