Schedule I - Condensed Financial Information of Parent (Balance Sheet Parenthetical) (Details) (Parent Company, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Parent Company
Condensed Financial Statements, Captions [Line Items]
Deferred financing costs, accumulated amortization	$ 81	$ 71

Carrying amount of accumulated amortization of long-term deferred finance costs capitalized at the end of the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

Name:	us-gaap_AccumulatedAmortizationOfNoncurrentDeferredFinanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant