v3.8.0.1

Schedule of Investments - Foreign Currency Forward Contracts (Detail) - 9 months ended Sep. 30, 2017		USD ($)	JPY (¥)	EUR (€)
ProShares UltraShort Euro [Member] | Contracts to Sell [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ 4,465,552
ProShares UltraShort Euro [Member] | Contracts to Sell [Member] | Euro with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 230,249,569		€ 194,781,925
Unrealized Appreciation (Depreciation)	[1]	$ 2,076,933
ProShares UltraShort Euro [Member] | Contracts to Sell [Member] | Euro with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 268,035,604		226,747,400
Unrealized Appreciation (Depreciation)	[1]	2,388,619
ProShares UltraShort Euro [Member] | Contracts to Purchase [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ (565,859)
ProShares UltraShort Euro [Member] | Contracts to Purchase [Member] | Euro with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 3,754,078		3,175,800
Unrealized Appreciation (Depreciation)	[1]	$ (42,918)
ProShares UltraShort Euro [Member] | Contracts to Purchase [Member] | Euro with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 41,453,378		35,067,900
Unrealized Appreciation (Depreciation)	[1]	(522,941)
ProShares UltraShort Yen [Member] | Contracts to Sell [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ 9,817,020
ProShares UltraShort Yen [Member] | Contracts to Sell [Member] | Yen with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ (155,971,917)	¥ (17,548,070,400)
Unrealized Appreciation (Depreciation)	[1]	$ 4,818,307
ProShares UltraShort Yen [Member] | Contracts to Sell [Member] | Yen with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ (168,708,480)	(18,981,034,100)
Unrealized Appreciation (Depreciation)	[1]	4,998,713
ProShares UltraShort Yen [Member] | Contracts to Purchase [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ (570,141)
ProShares UltraShort Yen [Member] | Contracts to Purchase [Member] | Yen with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 5,082,606	571,833,200
Unrealized Appreciation (Depreciation)	[1]	$ (229,963)
ProShares UltraShort Yen [Member] | Contracts to Purchase [Member] | Yen with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 22,573,065	2,539,647,800
Unrealized Appreciation (Depreciation)	[1]	(340,178)
ProShares Ultra Yen [Member] | Contracts to Sell [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ 12,351
ProShares Ultra Yen [Member] | Contracts to Sell [Member] | Yen with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ (206,978)	(23,286,700)
Unrealized Appreciation (Depreciation)	[1]	$ 1,919
ProShares Ultra Yen [Member] | Contracts to Sell [Member] | Yen with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ (508,163)	(57,172,300)
Unrealized Appreciation (Depreciation)	[1]	10,432
ProShares Ultra Yen [Member] | Contracts to Purchase [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ (407,660)
ProShares Ultra Yen [Member] | Contracts to Purchase [Member] | Yen with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 6,539,365	735,730,100
Unrealized Appreciation (Depreciation)	[1]	$ (218,377)
ProShares Ultra Yen [Member] | Contracts to Purchase [Member] | Yen with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 5,798,323	¥ 652,357,100
Unrealized Appreciation (Depreciation)	[1]	(189,283)
ProShares Ultra Euro [Member] | Contracts to Sell [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ 82,079
ProShares Ultra Euro [Member] | Contracts to Sell [Member] | Euro with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ (1,966,405)		(1,663,500)
Unrealized Appreciation (Depreciation)	[1]	$ 33,031
ProShares Ultra Euro [Member] | Contracts to Sell [Member] | Euro with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ (5,533,004)		(4,680,700)
Unrealized Appreciation (Depreciation)	[1]	49,048
ProShares Ultra Euro [Member] | Contracts to Purchase [Member]
Schedule of Investments [Line Items]
Unrealized Appreciation (Depreciation)	[1]	$ (291,439)
ProShares Ultra Euro [Member] | Contracts to Purchase [Member] | Euro with Goldman Sachs International [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 14,138,996		11,961,025
Unrealized Appreciation (Depreciation)	[1]	$ (136,124)
ProShares Ultra Euro [Member] | Contracts to Purchase [Member] | Euro with UBS AG [Member]
Schedule of Investments [Line Items]
Settlement Date	[1]	Oct. 06, 2017
Notional Amount	[1]	$ 20,774,032		€ 17,574,000
Unrealized Appreciation (Depreciation)	[1]	$ (155,315)
[1] The positions and counterparties herein are as of September 30, 2017. The Funds continually evaluate different counterparties for their transactions and counterparties are subject to change. New counterparties can be added at any time.

X

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Date the derivative contract matures, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeMaturityDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

X

- Definition

This element represents the net excess or deficiency of the fair value of an investment (security, contract) over or under its cost (face amount, notional amount), respectively, which excess value or deficiency has not been recognized in earnings of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=50485924&loc=SL6090603-123010

+ Details

Name:	us-gaap_InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortEuroMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=ck0001415311_EuroWithGoldmanSachsInternationalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=ck0001415311_EuroWithUbsAgMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraShortYenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=ck0001415311_YenWithGoldmanSachsInternationalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=ck0001415311_YenWithUbsAgMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraYenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ck0001415311_ProsharesUltraEuroMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: