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

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

- Definition

Cap rate on a foreign currency derivative for example, but not limited to, a cap or a collar.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeExchangeRateCap1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Floor rate on a foreign currency derivative for example, but not limited to, a floor or a collar.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeExchangeRateFloor1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

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

- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959

+ Details

Name:	us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=usdp_ForeignExchangeOptionMaturingin2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=usdp_ForegnExchangeOptionMaturingin2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) CAD in Millions	Jun. 30, 2015 CAD collar_arrangement $ / CAD	May. 30, 2014 CAD $ / CAD
Foreign Exchange Option/Maturing in 2016
Derivative [Line Items]
Number of derivative instruments held \| collar_arrangement	4
Notional amount	CAD 32.0
Exchange rate floor \| $ / CAD	0.84
Exchange rate cap \| $ / CAD	0.86
Foreign Exchange Option/Maturing in 2016 \| Minimum
Derivative [Line Items]
Notional amount	CAD 7.9
Foreign Exchange Option/Maturing in 2016 \| Maximum
Derivative [Line Items]
Notional amount	CAD 8.1
Foregn Exchange Option/Maturing in 2015
Derivative [Line Items]
Notional amount		CAD 37.2
Exchange rate floor \| $ / CAD		0.91
Exchange rate cap \| $ / CAD		0.93
Foregn Exchange Option/Maturing in 2015 \| Minimum
Derivative [Line Items]
Notional amount		CAD 7.3
Foregn Exchange Option/Maturing in 2015 \| Maximum
Derivative [Line Items]
Notional amount		CAD 7.5