v2.4.0.6

Investments (Offsetting Of Financial Liabilities And Derivative Liabilities) (Detail) (USD $) | Mar. 31, 2013 | Dec. 31, 2012
--- | --- | ---
ProShares UltraShort DJ-UBS Commodity [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | $ 92,919 |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 92,919 |  |  |
ProShares UltraShort DJ-UBS Commodity [Member] | Swap Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 92,919 |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 92,919 |  |  |
ProShares UltraShort DJ-UBS Crude Oil [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 12,719,387 |  | 6,586,396 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 12,719,387 |  | 6,586,396 |
ProShares UltraShort DJ-UBS Crude Oil [Member] | Swap Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 11,368,414 |  | 5,607,060 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 11,368,414 |  | 5,607,060 |
ProShares UltraShort DJ-UBS Crude Oil [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 1,350,973 | [1] | 979,336 | [1]
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 1,350,973 | [1] | 979,336 | [1]
ProShares UltraShort DJ-UBS Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  |  |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  |  |
ProShares UltraShort DJ-UBS Natural Gas [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  | [1] |  |
Gross Amounts Offset in the Statement of Financial Condition |  | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  | [1] |  |
ProShares UltraShort Gold [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 3,246,282 |  | 3,980 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 3,246,282 |  | 3,980 |
ProShares UltraShort Gold [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 3,980 | [1]
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 3,980 | [1]
ProShares UltraShort Gold [Member] | Forward Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 3,246,282 |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 3,246,282 |  |  |
ProShares UltraShort Silver [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 11,313 |  | 2,520 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 11,313 |  | 2,520 |
ProShares UltraShort Silver [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 2,520 | [1]
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 2,520 | [1]
ProShares UltraShort Silver [Member] | Forward Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 11,313 |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 11,313 |  |  |
ProShares Short Euro [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 12,300 |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 12,300 |  |  |
ProShares Short Euro [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 12,300 | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 12,300 | [1] |  |
ProShares UltraShort Australian Dollar [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 10,950 |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 10,950 |
ProShares UltraShort Australian Dollar [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  | [1] | 10,950 | [1]
Gross Amounts Offset in the Statement of Financial Condition |  | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  | [1] | 10,950 | [1]
ProShares UltraShort Euro [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 1,439,211 |  | 13,398,619 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 1,439,211 |  | 13,398,619 |
ProShares UltraShort Euro [Member] | Foreign Currency Forward Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 1,439,211 |  | 13,398,619 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 1,439,211 |  | 13,398,619 |
ProShares UltraShort Yen [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 232,642 |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 232,642 |
ProShares UltraShort Yen [Member] | Foreign Currency Forward Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 232,642 |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 232,642 |
ProShares Ultra DJ-UBS Commodity [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 306,268 |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 306,268 |
ProShares Ultra DJ-UBS Commodity [Member] | Swap Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 306,268 |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 306,268 |
ProShares Ultra DJ-UBS Crude Oil [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  |  |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  |  |
ProShares Ultra DJ-UBS Crude Oil [Member] | Swap Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  |  |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  |  |
ProShares Ultra DJ-UBS Crude Oil [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  | [1] |  |
Gross Amounts Offset in the Statement of Financial Condition |  | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  | [1] |  |
ProShares Ultra DJ-UBS Natural Gas [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 834,689 |  | 4,891,783 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 834,689 |  | 4,891,783 |
ProShares Ultra DJ-UBS Natural Gas [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 834,689 | [1] | 4,891,783 | [1]
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 834,689 | [1] | 4,891,783 | [1]
ProShares Ultra Gold [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 2,300 |  | 15,652,058 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 2,300 |  | 15,652,058 |
ProShares Ultra Gold [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 2,300 | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 2,300 | [1] |  |
ProShares Ultra Gold [Member] | Forward Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 15,652,058 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 15,652,058 |
ProShares Ultra Silver [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 8,109,608 |  | 145,740,706 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 8,109,608 |  | 145,740,706 |
ProShares Ultra Silver [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 2,890 | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 2,890 | [1] |  |
ProShares Ultra Silver [Member] | Forward Agreements [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 8,106,718 |  | 145,740,706 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 8,106,718 |  | 145,740,706 |
ProShares Ultra Australian Dollar [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 22,982 |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 22,982 |  |  |
ProShares Ultra Australian Dollar [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 22,982 | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 22,982 | [1] |  |
ProShares Ultra Euro [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 137,134 |  | 2,314 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 137,134 |  | 2,314 |
ProShares Ultra Euro [Member] | Foreign Currency Forward Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 137,134 |  | 2,314 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 137,134 |  | 2,314 |
ProShares Ultra Yen [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 70,562 |  | 507,819 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 70,562 |  | 507,819 |
ProShares Ultra Yen [Member] | Foreign Currency Forward Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 70,562 |  | 507,819 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 70,562 |  | 507,819 |
ProShares VIX Short-Term Futures ETF [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 2,471,348 |  | 31,540,181 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 2,471,348 |  | 31,540,181 |
ProShares VIX Short-Term Futures ETF [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 2,471,348 | [1] | 31,540,181 | [1]
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 2,471,348 | [1] | 31,540,181 | [1]
ProShares VIX Mid-Term Futures ETF [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  | 1,890,675 |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  | 1,890,675 |
ProShares VIX Mid-Term Futures ETF [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  | [1] | 1,890,675 | [1]
Gross Amounts Offset in the Statement of Financial Condition |  | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  | [1] | 1,890,675 | [1]
ProShares Ultra VIX Short-Term Futures ETF [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 4,961,933 |  | 35,666,735 |
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 4,961,933 |  | 35,666,735 |
ProShares Ultra VIX Short-Term Futures ETF [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities | 4,961,933 | [1] | 35,666,735 | [1]
Net Amounts of Liabilities Presented in the Statement of Financial Condition | 4,961,933 | [1] | 35,666,735 | [1]
ProShares Short VIX Short-Term Futures ETF [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  |  |  |
Gross Amounts Offset in the Statement of Financial Condition |  |  |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  |  |  |
ProShares Short VIX Short-Term Futures ETF [Member] | Future Contracts [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Gross Amounts of Recognized Liabilities |  | [1] |  |
Gross Amounts Offset in the Statement of Financial Condition |  | [1] |  |
Net Amounts of Liabilities Presented in the Statement of Financial Condition |  | [1] |  |
[1] | Current day's variation margin is reported within the Statements of Financial Condition in receivable/payable on open futures contracts; Cumulative appreciation/depreciation is reported in the Schedule of Investments.

X
- Definition Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -Subparagraph a -Clause 1 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount as of the balance sheet date of the fair value of derivative liabilities that in accordance with the entity's accounting policy were offset against the right to reclaim cash collateral under a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41678-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FIN39-1 -Paragraph 10B -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FIN39-1 -Paragraph 10A, 10B -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 4, 17 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611 + Details
Name: | us-gaap_DerivativeLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration