v2.4.0.8
Investments - Effect of Derivative Instruments on Statements of Operations (Detail) (USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]    
Realized Gain or (Loss) on Derivatives Recognized in Income $ 76,214,916 $ (230,349,276)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (53,072,999) 86,306,510
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 (635,695) 308,498
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 129,934 (241,421)
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 (12,278,001) (6,125,158)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (3,391,572) (1,500,109)
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 (9,215,034) (1,773,421)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 3,437,020 (3,905,888)
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 (22,149,687) 12,883,467
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 2,901,049 (6,992,788)
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 (12,614,405) 29,204,512
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 9,961,567 (19,064,897)
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 537,342 (508,897)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (129,206) 421,315
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 21,193,668 66,564,325
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 484,711 (28,737,943)
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 16,803,375 5,748,194
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 1,805,128 17,861,568
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 23,433,620 (50,415,205)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (5,199,398) 24,891,118
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 73,955,572 (215,688,548)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (55,636,611) 137,646,238
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 (66,588) (8,000)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 81,131 116,769
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 (78,609) 112,030
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (2,139,484) (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 (12,182,041) (2,949,680)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 10,024,197 26,813,021
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 (102,730) 96,886,297
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (24,540,300) (35,381,549)
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 (27,427) (149,275)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 311,205 223,960
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 85,136 (65,362)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (79,978) (221,155)
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 (10,517) (1,217,971)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 118,080 423,734
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 15,779,707 (55,408,949)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 11,625,721 (8,124,641)
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 (5,397,902) (10,260,171)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income 2,889,479 (406,019)
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 (3,546,304) (122,690,073)
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income (5,691,916) (21,095,534)
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 2,731,436 25,204,111
Change in Unrealized Appreciation or Depreciation on Derivatives Recognized in Income $ (33,756) $ 3,775,891