Derivative Instruments and Hedging Activities Viento II Swap Termination Fees (Details) (Interest rate contracts, USD $) In Millions, unless otherwise specified	0 Months Ended
Jul. 11, 2013
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Payments for Fees	$ 6

The amount of cash paid during the current period for fees which are not defined elsewhere in the taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3536-108585

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 27

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_PaymentsForFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration