v2.4.0.8
Investments - Effect of Derivative Instruments on Statements of Operations (Detail) (USD $)
3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income $ (341,755,684) $ (225,181,050) $ (265,540,768) $ (455,530,326)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 90,346,405 (140,296,240) 37,273,406 (53,989,730)
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 Commodity [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income 130,061 150,169 (505,634) 458,667
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (151,988) 505,167 (22,054) 263,746
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 or (Loss) on Derivatives Recognized in Income (31,567,008) 1,025,654 (43,845,009) (5,099,504)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (14,316,548) 9,878,372 (17,708,120) 8,378,263
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 or (Loss) on Derivatives Recognized in Income (1,970,509) (834,719) (11,185,543) (2,608,140)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (2,011,476) 5,826,227 1,425,544 1,920,339
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 13,875,395 20,858,050 (8,274,292) 33,741,517
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (19,136,970) 55,074,622 (16,235,921) 48,081,834
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 12,455,116 51,615,327 (159,289) 80,819,839
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (18,328,033) 40,886,777 (8,366,466) 21,821,880
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 Commodity [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income (160,396) (274,078) 376,946 (782,975)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 123,172 (586,322) (6,034) (165,007)
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 or (Loss) on Derivatives Recognized in Income 9,814,101 20,733,669 31,007,769 87,297,994
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 2,164,869 (22,057,265) 2,649,580 (50,795,208)
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 or (Loss) on Derivatives Recognized in Income 162,451 9,153,747 16,965,826 14,901,941
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 440,646 (19,990,856) 2,245,774 (2,129,288)
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 (21,489,136) (68,008,649) 1,944,484 (118,423,854)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 25,259,667 (62,970,484) 20,060,269 (38,079,366)
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 (106,239,950) (322,610,723) (32,284,378) (538,299,271)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 145,054,357 (168,439,871) 89,417,746 (30,793,633)
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or Foreign Currency Forward Contracts [Member] | ProShares Short Euro [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income 225,122 (67,938) 158,534 (75,938)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (159,059) 5,900 (77,928) 122,669
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or 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 (1,846,929) 1,793,067 (1,925,538) 1,905,097
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 859,039 1,508,211 (1,280,445) 1,313,051
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or Foreign Currency Forward Contracts [Member] | ProShares UltraShort Euro [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income 5,886,956 (8,147,050) (6,295,085) (11,096,730)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (1,863,031) (8,918,725) 8,161,166 17,894,296
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or Foreign Currency Forward Contracts [Member] | ProShares UltraShort Yen [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income 268,536 48,138,405 165,806 145,024,702
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (14,493,994) (6,860,712) (39,034,294) (42,242,261)
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or 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 285,670 (590,630) 258,243 (739,905)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (129,485) (332,037) 181,720 (108,077)
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or Foreign Currency Forward Contracts [Member] | ProShares Ultra Euro [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income (40,251) 36,991 44,885 (28,371)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 9,743 96,965 (70,235) (124,190)
Foreign Exchange Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or Foreign Currency Forward Contracts/Changes in Unrealized Appreciation/ Depreciation on Futures Contracts and/or Foreign Currency Forward Contracts [Member] | ProShares Ultra Yen [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income (11,079) (456,601) (21,596) (1,674,572)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 93,948 80,626 212,028 504,360
VIX Futures Contracts [Member] | Net Realized Gain Loss On Futures Contracts And Swap Agreements Changes In Unrealized Appreciation Depreciation On Futures Contracts And Swap Agreements [Member] | ProShares VIX Short-Term Futures ETF [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income   11,156,344   (44,252,605)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income   9,582,597   1,457,956
VIX Futures Contracts [Member] | Net Realized Gain Loss On Futures Contracts And Swap Agreements Changes In Unrealized Appreciation Depreciation On Futures Contracts And Swap Agreements [Member] | ProShares VIX Mid-Term Futures ETF [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income   (2,486,914)   (12,747,085)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income   7,458,863   7,052,844
VIX Futures Contracts [Member] | Net Realized Gain Loss On Futures Contracts And Swap Agreements Changes In Unrealized Appreciation Depreciation On Futures Contracts And Swap Agreements [Member] | ProShares Ultra VIX Short-Term Futures ETF [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income   17,763,794   (104,926,279)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income   21,978,092   882,558
VIX Futures Contracts [Member] | Net Realized Gain Loss On Futures Contracts And Swap Agreements Changes In Unrealized Appreciation Depreciation On Futures Contracts And Swap Agreements [Member] | ProShares Short VIX Short-Term Futures ETF [Member]
       
Derivative Instruments, Gain (Loss) [Line Items]        
Realized Gain or (Loss) on Derivatives Recognized in Income   (4,128,965)   21,075,146
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income   (3,022,387)   753,504
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 (41,227,047)   (25,447,340)  
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (1,586,521)   10,039,200  
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 (6,666,419)   (12,064,321)  
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (1,487,840)   1,401,639  
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 (247,176,983)   (250,723,287)  
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (10,831,519)   (16,523,435)  
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 73,536,615   76,268,051  
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income $ 837,428   $ 803,672