Statements of Changes in Net Assets - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Statements of Changes in Net Assets [Abstract]
Opening balance (in Shares)		6,400,000	5,450,000	5,450,000
Creations (in Shares)		1,300,000		1,650,000
Redemptions (in Shares)		(1,300,000)		(700,000)
Closing balance (in Shares)	6,400,000	6,400,000		6,400,000
Opening balance		$ 565,459	$ 473,978	$ 473,978
Net investment loss	$ (742)	(2,292)	(2,348)	(3,186)
Realized loss on investment in platinum		(29,202)		(18,387)
Change in unrealized gain (loss) on investment in platinum	(15,334)	(27,030)	$ 22,469	28,648
Creations		102,889		148,038
Redemptions		(114,917)		(63,632)
Closing balance	$ 494,907	$ 494,907		$ 565,459