Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	3 Months Ended	9 Months Ended
Sep. 30, 2013	Mar. 31, 2013 OKCD [Member]	Sep. 30, 2012 OKCD [Member]	Sep. 30, 2012 OKCD [Member]
Partnership interests	84.00%
Related party payment		$ 0.6	$ 1.8	$ 5.6

The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 22

-Article 12

Name:	us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration