Name:	gxp_ContractuallySpecifiedServicingFeesPercentageAmount
Namespace Prefix:	gxp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Maximum amount of outstanding principal under receivables agreement

No definition available.

Name:	gxp_MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreement
Namespace Prefix:	gxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Maximum amount of outstanding principal under receivables agreement from June 1 to October 31 of each year.

No definition available.

Name:	gxp_MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromJune1ToOctober31OfEachYear
Namespace Prefix:	gxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Maximum amount of outstanding principal under receivables agreement from November 1 to May 31 of each year

No definition available.

Name:	gxp_MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromNovember1ToMay31OfEachYear
Namespace Prefix:	gxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying amount of financial assets accounted for as secured borrowings recognized in the transferor's statement of financial position at the end of each period presented.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=7523297&loc=SL6224234-111729

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

Carrying amount of liabilities associated with financial assets accounted for as secured borrowings recognized in the transferor's statement of financial position at the end of each period presented.