Per-share or per-unit cash distributions paid to a common shareholder or unit-holder by an LLC or LP.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of incentive obligation paid in cash or stock during the period to a limited liability corporation managing member or limited partnership general partner.

+ References

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 07-4

-Paragraph 2, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Distribution per share limit for percentage allocation

+ References

No definition available.

+ Details

Name:	xtxi_DistributionPerUnitExcessDistributionLevel
Namespace Prefix:	xtxi_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Per-share or per-unit amount of incentive dividend declared and paid to managing member in excess of regular amount

+ References

No definition available.

+ Details

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Namespace Prefix:	xtxi_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Different percentage level for each distribution excess allocated to General Partners

+ References

No definition available.

+ Details

Name:	xtxi_IncentiveDistributionPercentageLevels
Namespace Prefix:	xtxi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period between quarter ends when distributions should be made per partnership agreement

+ References

No definition available.

+ Details

Name:	xtxi_NumberOfDaysBeforeDistribution
Namespace Prefix:	xtxi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of the total distribution allocated to the limited partners.

+ References

No definition available.

+ Details

Name:	xtxi_PercentageOfDistributionAllocatedToLimitedPartners
Namespace Prefix:	xtxi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Public Offering of units and Certain Provisions of the Partnership Agreement (Distribution) (Details Textuals) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Distribution Made to Member or Limited Partner [Line Items]
Distribution per unit excess distribution level	$ 0.2125
Number Of Days Before Distribution	45
General Partner [Member]
Distribution Made to Member or Limited Partner [Line Items]
Distribution Made to Member or Limited Partner, Distributions Paid, Per Unit	$ 1.31	$ 1.17	$ 0.25
General Partner [Member] \| Incentive Distribution Distribution Per Unit [Member] \| Thirteen Percent [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distibution Excess Per Unit Amount	$ 0.25
General Partner [Member] \| Incentive Distribution Distribution Per Unit [Member] \| Twenty three Percent [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distibution Excess Per Unit Amount	$ 0.3125
General Partner [Member] \| Incentive Distribution Distribution Per Unit [Member] \| Fortyeight Percent [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distibution Excess Per Unit Amount	$ 0.375
General Partner [Member] \| Incentive Distribution Percentage [Member]
Distribution Made to Member or Limited Partner [Line Items]
Percentage of distribution allocated to limited partners	100.00%
General Partner [Member] \| Incentive Distribution Percentage [Member] \| Thirteen Percent [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distribution Percentage Levels	13.00%
General Partner [Member] \| Incentive Distribution Percentage [Member] \| Twenty three Percent [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distribution Percentage Levels	23.00%
General Partner [Member] \| Incentive Distribution Percentage [Member] \| Fortyeight Percent [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distribution Percentage Levels	48.00%
General Partner [Member] \| Cash Distribution [Member]
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distribution, Distribution	$ 4.5	$ 2.4	$ 0.1