Represents a decrease in noncontrolling interest from issuance of additional equity interests to noncontrolling interest holders or the sale of a portion of the parent's controlling interest.

No definition available.

Name:	xtxi_MinorityInterestDecreaseFromStockIssuance
Namespace Prefix:	xtxi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Public Offering of units and Certain Provisions of the Partnership Agreement (Textuals) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012	May 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Partners' Capital Notes [Abstract]
Minority Interest Decrease From Stock Issuance		$ 3.6	$ 12.3
Deferred Tax Liabilities Investments Decrease		6.0	5.1
Company Share Of Partnership Income loss	$ 15.5			$ 6.4	$ 11.6