v3.8.0.1

Investments - Effect of Derivative Instruments on Statements of Operations (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	$ 44,744,372	$ (699,779,052)	$ (442,967,392)	$ (1,302,568,955)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	85,175,327	153,774,452	(54,146,134)	158,526,436
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	(27,447,205)	(101,785,229)	(126,202,705)	(134,345,928)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(17,219,461)	6,786,934	(17,860,669)	(8,475,358)
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	(3,965,084)	(4,899,530)	(19,180,135)	(5,248,725)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	364,615	(1,149,750)	(653,395)	(1,917,790)
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	188,300,727	277,246,086	471,128,319	263,024,643
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	100,033,466	(51,813,012)	104,553,646	16,663,427
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	(126,532,816)	(745,101,700)	(646,036,987)	(1,269,233,467)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(95,515,562)	138,973,918	(93,790,794)	(51,163,549)
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	(9,418,807)	50,281,494	49,807,530	(36,896,214)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(30,456,798)	(32,976,232)	(5,412,170)	(29,823,971)
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] | Pro Shares UltraPro 3X Short Crude Oil ETF [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(1,540,337)		232,006
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(2,178,096)		(2,423,370)
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	(151,368)	(101,997)	1,756,252	455,516
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	615,201	712,984	830,552	2,803,566
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	(2,644,155)	(10,296,533)	(10,938,952)	(29,965,169)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	299,106	9,770,795	(100,481)	(231,807)
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	(467,171)	(14,865,870)	(2,693,320)	(26,655,192)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(393,756)	9,507,258	745,817	(4,267,196)
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	45,497,245	(246,218,628)	(123,511,840)	(132,872,456)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	112,823,127	165,582,895	(6,281,183)	190,316,382
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	4,971,742		3,137,907
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	694,326		1,272,779
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	(2,014,548)	1,964,411	(21,040,313)	6,591,697
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(1,078,511)	(8,409,834)	(3,508,410)	(7,752,693)
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	5,462,918	12,629,891	23,362,749	33,703,970
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(549,421)	(13,416,914)	(3,993,840)	(204,134)
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	1,064,270	119,372,366	20,327,016	174,870,519
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	7,159,593	(88,240,470)	(7,245,193)	9,826,416
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	(599,482)	327,212	(1,334,988)	(199,588)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	291,787	(488,475)	(26,694)	(270,444)
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	(1,453,355)	(318,842)	(1,920,606)	(2,462,334)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	837,800	(971,687)	(802,850)	(495,700)
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	(24,505,520)	(5,537,097)	(45,334,575)	(60,591,547)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	10,103,133	(2,518,631)	(12,263,238)	30,435,313
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	(1,067,853)	(33,476,385)	(17,529,013)	(86,173,771)
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(83,509)	23,071,090	(7,498,058)	14,006,768
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	1,259,663	46,252	2,666,172	1,155,961
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	(519,273)	118,030	364,650	(654,504)
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	(4,492)	955,047	338,091	2,273,130
Change in Unrealized Appreciation/ Depreciation on Derivatives Recognized in Income	$ (52,440)	$ (764,447)	$ (53,233)	$ (268,290)

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+ References

Reference 1: 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=84234895&loc=SL5618551-113959

Reference 2: 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=84234895&loc=SL5624171-113959

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