v3.10.0.1

Investments - Effect of Derivative Instruments on Statements of Operations (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	$ (92,109,013)	$ (180,675,672)	$ (1,428,741,022)	$ (487,711,764)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	55,761,957	1,042,587	40,222,543	(139,321,461)
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or swap agreements/Changes in Unrealized Appreciation/Depreciation on Futures Contracts and/or swap agreements [Member] | ProShares Short VIX Short-Term Futures ETF [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	56,008,377		(1,827,517,354)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	14,232,558		(39,569,847)
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or swap agreements/Changes in Unrealized Appreciation/Depreciation on Futures Contracts and/or swap agreements [Member] | ProShares Ultra VIX Short-Term Futures ETF [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(155,817,104)		260,792,676
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	7,071,541		74,528,029
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or swap agreements/Changes in Unrealized Appreciation/Depreciation on Futures Contracts and/or swap agreements [Member] | ProShares VIX Mid-Term Futures ETF [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	247,018		3,967,454
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(3,080,525)		1,837,040
VIX Futures Contracts [Member] | Net Realized Gain (Loss) on Futures Contracts and/or swap agreements/Changes in Unrealized Appreciation/Depreciation on Futures Contracts and/or swap agreements [Member] | ProShares VIX Short-Term Futures ETF [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(23,529,528)		53,747,452
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	177,711		14,188,337
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		182,934,500		282,827,592
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income		(24,640,794)		4,520,180
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		(153,988,983)		(519,504,171)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income		30,318,423		1,724,768
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		(7,047,733)		(15,215,051)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income		2,246,125		(1,018,010)
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		(33,527,643)		(98,755,500)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income		6,215,600		(641,208)
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 Crude Oil [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	39,220,725	(168,596,998)	151,738,616	(169,009,085)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	64,077,371	28,760,997	25,533,633	(119,104,310)
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 Bloomberg Natural Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	3,945,962	(4,648,049)	5,080,774	(19,025,765)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(2,369,992)	(3,330,323)	(7,344,433)	(2,429,899)
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	(5,706,990)	8,452,341	2,948,285	17,899,831
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(5,799,159)	(9,844,776)	(10,819,851)	(3,444,419)
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	(5,627,237)	(10,939,142)	7,174,506	19,262,746
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(4,043,563)	(41,686,389)	(35,893,615)	(14,404,786)
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	1,740,951	(1,832,876)	3,361,776	(1,833,835)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	6,901,529	(272,129)	8,487,486	578,453
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 UltraPro 3X Short Crude Oil ETF [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(6,793,148)	1,878,109	(11,469,115)	1,772,343
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(1,707,316)	416,232	(2,454,299)	(245,274)
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	(27,663,521)	60,376,204	(75,759,671)	59,226,337
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(21,642,290)	(14,895,206)	(6,360,359)	25,044,628
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 UltraShort Bloomberg Natural Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(759,484)	49,239	(12,513)	1,907,620
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	171,317	881,105	1,103,321	215,351
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	1,572,920	(3,423,637)	(1,696,955)	(8,294,797)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	1,879,470	3,811,095	3,785,409	(399,587)
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	334,485	631,112	(1,262,356)	(2,226,149)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	475,292	3,022,382	3,178,568	1,139,573
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	443,811	(817,763)	64,225	(735,506)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	16,282	(65,818)	253,501	(318,481)
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	(1,110,032)	2,035,177	(309,519)	1,406,509
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	46,013	(10,405)	(436,206)	883,923
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	(299,704)	424,094	22,846	342,583
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	22,366	(590,497)	10,565	(793)
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	415,369	64,976	(704,621)	(467,251)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	93,610	(208,036)	1,284,990	(1,640,650)
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	22,934,693	(36,508,674)	4,011,451	(20,829,055)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(342,410)	1,694,586	9,744,219	(22,366,371)
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	8,333,424	(16,189,926)	(2,918,979)	(16,461,160)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	$ (417,848)	$ 19,220,415	$ (833,945)	$ (7,414,549)

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+ References

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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