v3.8.0.1
Significant Accounting Policies (Schedule Of Investment In Palladium) (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2018
USD ($)
oz
Mar. 31, 2017
USD ($)
oz
Dec. 31, 2017
USD ($)
oz
Significant Accounting Policies [Abstract]      
Opening balance (in Ounces) | oz 228,863.1 263,819.3 263,819.3
Creations (in Ounces) | oz 14,288.0   43,021.8
Redemptions (in Ounces) | oz (4,763.0)   (76,489.4)
Transfers of palladium to pay expenses (in Ounces) | oz (343.4)   (1,488.6)
Closing balance (in Ounces) | oz 238,044.7   228,863.1
Investment in palladium, fair value, Opening balance $ 241,679 $ 178,342 $ 178,342
Creations 14,926   37,402
Redemptions (4,949)   (64,629)
Realized gain on palladium distributed for the redemption of Shares 1,674 1,138 14,337
Transfers of palladiuim to pay expenses (363)   (1,244)
Realized gain on palladium transferred to pay expenses 127 34 266
Change in unrealized (loss) / gain on investment in palladium (22,191) $ 30,623 77,205
Investment in palladium, fair value, closing balance $ 230,903   $ 241,679