Organization	12 Months Ended
Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	Note 1 – Organization PowerShares DB US Dollar Index Bearish Fund (the “Fund”), a separate series of PowerShares DB US Dollar Index Trust (the “Trust”) was formed as a Delaware statutory trust on August 3, 2006. The term of the Fund is perpetual (unless terminated earlier in certain circumstances) as provided for in the Fifth Amended and Restated Declaration of Trust and Trust Agreement of the Trust, as amended (the “Trust Agreement”). The Fund has an unlimited number of shares authorized for issuance. Invesco PowerShares Capital Management LLC (“Invesco”) has served as the managing owner (the “Managing Owner”), commodity pool operator and a commodity trading advisor of the Trust and the Fund since February 23, 2015 (the “Closing Date”). Prior to the Closing Date, a different company served the Fund in those capacities (the “Predecessor Managing Owner”). The Predecessor Managing Owner seeded the Fund with a capital contribution of $1,000 in exchange for 40 general shares (the “General Shares”) of the Fund. The General Shares were sold to the Managing Owner by the Predecessor Managing Owner pursuant to the terms of the asset purchase agreement entered into with DB US Financial Markets Holding Corporation. The fiscal year end of the Fund is December 31st. The Fund establishes short positions in certain futures contracts (the “DX Contracts”) with a view to tracking the changes, whether positive or negative, in the level of the Deutsche Bank Short USD Currency Portfolio Index–Excess Return^TM (the “Index”) over time. The Index was renamed effective January 17, 2017. Prior to January 17, 2017, the Index was known as the Deutsche Bank Short US Dollar Index (USDX®) Futures Index–Excess Return^TM. The Index, as renamed, is identical to the Index prior to its name change on January 17, 2017. The performance of the Fund also is intended to reflect the excess, if any, of the sum of the Fund’s interest income from its holdings of United States Treasury Obligations, dividends from its holdings in money market mutual funds (affiliated or otherwise) and dividends or distributions of capital gains from its holdings of T-Bill ETFs (as defined below) over the expenses of the Fund. The Fund may invest directly in United States Treasury Obligations. The Fund may also gain exposure to United States Treasury Obligations through investments in exchange-traded funds (“ETSs”) (affiliated or otherwise) that track indexes that measure the performance of United States Treasury Obligations with a maximum remaining maturity of up to 12 months (“T-Bill ETFs”). The Fund invests in United States Treasury Obligations, money market mutual funds and T-Bill ETFs (affiliated or otherwise), if any, for margin and/or cash management purposes. The Fund offers common units of beneficial interest (the “Shares”) only to certain eligible financial institutions (the “Authorized Participants”) in one or more blocks of 200,000 Shares, called a Basket. The Fund commenced investment operations on February 15, 2007. The Fund commenced trading on the American Stock Exchange (which became the NYSE Alternext US LLC) on February 20, 2007 and, since November 25, 2008, has been listed on the NYSE Arca, Inc. (the “NYSE Arca”). This Annual Report (the “Report”) covers the years ended December 31, 2017, 2016 and 2015. The Fund’s performance information from inception up to and excluding the Closing Date is a reflection of the performance associated with the Predecessor Managing Owner. The Managing Owner has served as managing owner of the Fund since the Closing Date, and the Fund’s performance information since the Closing Date is a reflection of the performance associated with the Managing Owner. Past performance of the Fund is not necessarily indicative of future performance.

Note 1 – Organization

PowerShares DB US Dollar Index Bearish Fund (the “Fund”), a separate series of PowerShares DB US Dollar Index Trust (the “Trust”) was formed as a Delaware statutory trust on August 3, 2006. The term of the Fund is perpetual (unless terminated earlier in certain circumstances) as provided for in the Fifth Amended and Restated Declaration of Trust and Trust Agreement of the Trust, as amended (the “Trust Agreement”). The Fund has an unlimited number of shares authorized for issuance.

Invesco PowerShares Capital Management LLC (“Invesco”) has served as the managing owner (the “Managing Owner”), commodity pool operator and a commodity trading advisor of the Trust and the Fund since February 23, 2015 (the “Closing Date”). Prior to the Closing Date, a different company served the Fund in those capacities (the “Predecessor Managing Owner”). The Predecessor Managing Owner seeded the Fund with a capital contribution of $1,000 in exchange for 40 general shares (the “General Shares”) of the Fund. The General Shares were sold to the Managing Owner by the Predecessor Managing Owner pursuant to the terms of the asset purchase agreement entered into with DB US Financial Markets Holding Corporation. The fiscal year end of the Fund is December 31st.

The Fund establishes short positions in certain futures contracts (the “DX Contracts”) with a view to tracking the changes, whether positive or negative, in the level of the Deutsche Bank Short USD Currency Portfolio Index–Excess Return^TM (the “Index”) over time. The Index was renamed effective January 17, 2017. Prior to January 17, 2017, the Index was known as the Deutsche Bank Short US Dollar Index (USDX®) Futures Index–Excess Return^TM. The Index, as renamed, is identical to the Index prior to its name change on January 17, 2017. The performance of the Fund also is intended to reflect the excess, if any, of the sum of the Fund’s interest income from its holdings of United States Treasury Obligations, dividends from its holdings in money market mutual funds (affiliated or otherwise) and dividends or distributions of capital gains from its holdings of T-Bill ETFs (as defined below) over the expenses of the Fund.

The Fund may invest directly in United States Treasury Obligations. The Fund may also gain exposure to United States Treasury Obligations through investments in exchange-traded funds (“ETSs”) (affiliated or otherwise) that track indexes that measure the performance of United States Treasury Obligations with a maximum remaining maturity of up to 12 months (“T-Bill ETFs”). The Fund invests in United States Treasury Obligations, money market mutual funds and T-Bill ETFs (affiliated or otherwise), if any, for margin and/or cash management purposes.

The Fund offers common units of beneficial interest (the “Shares”) only to certain eligible financial institutions (the “Authorized Participants”) in one or more blocks of 200,000 Shares, called a Basket. The Fund commenced investment operations on February 15, 2007. The Fund commenced trading on the American Stock Exchange (which became the NYSE Alternext US LLC) on February 20, 2007 and, since November 25, 2008, has been listed on the NYSE Arca, Inc. (the “NYSE Arca”).

This Annual Report (the “Report”) covers the years ended December 31, 2017, 2016 and 2015. The Fund’s performance information from inception up to and excluding the Closing Date is a reflection of the performance associated with the Predecessor Managing Owner. The Managing Owner has served as managing owner of the Fund since the Closing Date, and the Fund’s performance information since the Closing Date is a reflection of the performance associated with the Managing Owner. Past performance of the Fund is not necessarily indicative of future performance.