v3.8.0.1

Investments - Effect of Derivative Instruments on Statements of Operations (Detail) - USD ($) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | $ 44,744,372 | $ (699,779,052) | $ (442,967,392) | $ (1,302,568,955)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 85,175,327 | 153,774,452 | (54,146,134) | 158,526,436
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts / Changes in Unrealized Appreciation/ Depreciation on Futures Contracts [Member] | ProShares VIX Short-Term Futures ETF [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (27,447,205) | (101,785,229) | (126,202,705) | (134,345,928)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (17,219,461) | 6,786,934 | (17,860,669) | (8,475,358)
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts / Changes in Unrealized Appreciation/ Depreciation on Futures Contracts [Member] | ProShares VIX Mid-Term Futures ETF [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (3,965,084) | (4,899,530) | (19,180,135) | (5,248,725)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 364,615 | (1,149,750) | (653,395) | (1,917,790)
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts / Changes in Unrealized Appreciation/ Depreciation on Futures Contracts [Member] | ProShares Short VIX Short-Term Futures ETF [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | 188,300,727 | 277,246,086 | 471,128,319 | 263,024,643
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 100,033,466 | (51,813,012) | 104,553,646 | 16,663,427
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts / Changes in Unrealized Appreciation/ Depreciation on Futures Contracts [Member] | ProShares Ultra VIX Short-Term Futures ETF [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (126,532,816) | (745,101,700) | (646,036,987) | (1,269,233,467)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (95,515,562) | 138,973,918 | (93,790,794) | (51,163,549)
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares UltraShort Bloomberg Crude Oil [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (9,418,807) | 50,281,494 | 49,807,530 | (36,896,214)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (30,456,798) | (32,976,232) | (5,412,170) | (29,823,971)
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | Pro Shares UltraPro 3X Short Crude Oil ETF [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (1,540,337) |  | 232,006 |
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (2,178,096) |  | (2,423,370) |
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares UltraShort Bloomberg Natural Gas [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (151,368) | (101,997) | 1,756,252 | 455,516
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 615,201 | 712,984 | 830,552 | 2,803,566
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares UltraShort Gold [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (2,644,155) | (10,296,533) | (10,938,952) | (29,965,169)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 299,106 | 9,770,795 | (100,481) | (231,807)
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares UltraShort Silver [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (467,171) | (14,865,870) | (2,693,320) | (26,655,192)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (393,756) | 9,507,258 | 745,817 | (4,267,196)
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares Ultra Bloomberg Crude Oil [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | 45,497,245 | (246,218,628) | (123,511,840) | (132,872,456)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 112,823,127 | 165,582,895 | (6,281,183) | 190,316,382
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | Proshares Ultra Pro 3X Crude Oil ETF [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | 4,971,742 |  | 3,137,907 |
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 694,326 |  | 1,272,779 |
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares Ultra Bloomberg Natural Gas [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (2,014,548) | 1,964,411 | (21,040,313) | 6,591,697
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (1,078,511) | (8,409,834) | (3,508,410) | (7,752,693)
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares Ultra Gold [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | 5,462,918 | 12,629,891 | 23,362,749 | 33,703,970
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (549,421) | (13,416,914) | (3,993,840) | (204,134)
Commodity Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts, Swap and/or Forward Agreements/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts, Swap and/or Forward Agreements [Member] | ProShares Ultra Silver [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | 1,064,270 | 119,372,366 | 20,327,016 | 174,870,519
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 7,159,593 | (88,240,470) | (7,245,193) | 9,826,416
Foreign Exchange Contracts [Member] | Net realized gain (loss) on futures and/or foreign currency forward contracts/changes in unrealized appreciation/ depreciation on futures and/or foreign currency forward contracts [Member] | ProShares Short Euro [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (599,482) | 327,212 | (1,334,988) | (199,588)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 291,787 | (488,475) | (26,694) | (270,444)
Foreign Exchange Contracts [Member] | Net realized gain (loss) on futures and/or foreign currency forward contracts/changes in unrealized appreciation/ depreciation on futures and/or foreign currency forward contracts [Member] | ProShares UltraShort Australian Dollar [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (1,453,355) | (318,842) | (1,920,606) | (2,462,334)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 837,800 | (971,687) | (802,850) | (495,700)
Foreign Exchange Contracts [Member] | Net realized gain (loss) on futures and/or foreign currency forward contracts/changes in unrealized appreciation/ depreciation on futures and/or foreign currency forward contracts [Member] | ProShares UltraShort Euro [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (24,505,520) | (5,537,097) | (45,334,575) | (60,591,547)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | 10,103,133 | (2,518,631) | (12,263,238) | 30,435,313
Foreign Exchange Contracts [Member] | Net realized gain (loss) on futures and/or foreign currency forward contracts/changes in unrealized appreciation/ depreciation on futures and/or foreign currency forward contracts [Member] | ProShares UltraShort Yen [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (1,067,853) | (33,476,385) | (17,529,013) | (86,173,771)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (83,509) | 23,071,090 | (7,498,058) | 14,006,768
Foreign Exchange Contracts [Member] | Net realized gain (loss) on futures and/or foreign currency forward contracts/changes in unrealized appreciation/ depreciation on futures and/or foreign currency forward contracts [Member] | ProShares Ultra Euro [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | 1,259,663 | 46,252 | 2,666,172 | 1,155,961
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | (519,273) | 118,030 | 364,650 | (654,504)
Foreign Exchange Contracts [Member] | Net realized gain (loss) on futures and/or foreign currency forward contracts/changes in unrealized appreciation/ depreciation on futures and/or foreign currency forward contracts [Member] | ProShares Ultra Yen [Member] |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Realized Gain (Loss) on Derivatives Recognized in Income | (4,492) | 955,047 | 338,091 | 2,273,130
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income | $ (52,440) | $ (764,447) | $ (53,233) | $ (268,290)

X
- Definition Change in unrealized appreciation/ depreciation on derivatives recognized in income. + References No definition available. + Details
Name: | ck0001415311_ChangeInUnrealizedAppreciationDepreciationOnDerivativesRecognizedInIncome
Namespace Prefix: | ck0001415311_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
Name: | us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ck0001415311_VolatilityIndexFutureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=ck0001415311_NetRealizedGainLossOnFuturesContractsChangesInUnrealizedAppreciationDepreciationOnFuturesContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesVixShortTermFuturesEtfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesVixMidTermFuturesEtfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesShortVixShortTermFuturesEtfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraVixShortTermFuturesEtfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=ck0001415311_NetRealizedGainLossOnFuturesContractsSwapAndOrForwardAgreementsChangesInUnrealizedAppreciationDepreciationOnFuturesContractsSwapAndOrForwardAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortBloombergCrudeOilMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraProThreeXShortCrudeOilEtfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortBloombergNaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortGoldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortSilverMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraBloombergCrudeOilMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraProThreexCrudeOilEtfMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraBloombergNaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraGoldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraSilverMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=ck0001415311_NetRealizedGainLossOnFuturesContractsOrForwardAgreementsChangesInUnrealizedAppreciationDepreciationOnFuturesContractsOrForwardAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesShortEuroMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortAustralianDollarMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortEuroMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortYenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraEuroMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraYenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |