v2.4.0.6

Investments (Effect Of Derivative Instruments On Statements Of Operations) (Detail) (USD $) | 3 Months Ended
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Mar. 31, 2013 | Mar. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | $ (230,349,276) | $ (166,787,901)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 86,306,510 | 4,840,424
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 DJ-UBS Commodity [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | 308,498 | 74,310
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (241,421) | (361,088)
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 DJ-UBS Crude Oil [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (6,125,158) | (3,831,611)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (1,500,109) | (901,690)
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 DJ-UBS Natural Gas [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (1,773,421) | 4,437,111
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (3,905,888) | 5,930,960
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 or (Loss) on Derivatives Recognized in Income | 12,883,467 | (1,545,985)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (6,992,788) | (33,068,073)
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 or (Loss) on Derivatives Recognized in Income | 29,204,512 | (35,684,414)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (19,064,897) | (34,342,752)
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 DJ-UBS Commodity [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (508,897) | (322,448)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 421,315 | 421,325
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 DJ-UBS Crude Oil [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | 66,564,325 | 15,544,135
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (28,737,943) | 9,089,628
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 DJ-UBS Natural Gas [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | 5,748,194 | (5,158,571)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 17,861,568 | (15,543,310)
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 or (Loss) on Derivatives Recognized in Income | (50,415,205) | (29,858,796)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 24,891,118 | 76,461,894
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 or (Loss) on Derivatives Recognized in Income | (215,688,548) | 8,106,450
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 137,646,238 | 132,908,783
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares Short Euro [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (8,000) |
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 116,769 |
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares UltraShort Australian Dollar [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | 112,030 |
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (195,160) |
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares UltraShort Euro [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (2,949,680) | 38,812,588
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 26,813,021 | (98,488,552)
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares UltraShort Yen [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | 96,886,297 | 20,853,004
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (35,381,549) | 17,433,639
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares Ultra Australian Dollar [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (149,275) |
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 223,960 |
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares Ultra Euro [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (65,362) | (249,576)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (221,155) | 811,782
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) On Foreign Currency Forward Contracts/ Changes In Unrealized Appreciation/ Depreciation On Foreign Currency Forward Contracts [Member] | ProShares Ultra Yen [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Realized Gain or (Loss) on Derivatives Recognized in Income | (1,217,971) | (425,209)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | 423,734 | (328,692)
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 or (Loss) on Derivatives Recognized in Income | (55,408,949) | (42,732,137)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (8,124,641) | (17,345,947)
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 or (Loss) on Derivatives Recognized in Income | (10,260,171) | (22,417,600)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (406,019) | (5,041,600)
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 or (Loss) on Derivatives Recognized in Income | (122,690,073) | (119,246,992)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | (21,095,534) | (33,611,433)
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 or (Loss) on Derivatives Recognized in Income | 25,204,111 | 6,857,840
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income | $ 3,775,891 | $ 815,550

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- Definition The amount of net gains and losses recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments. + References Reference 1: 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=7476318&loc=SL5624171-113959 Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -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. Reference 4: 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=7476318&loc=SL5618551-113959 + Details
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