Fair Value Measurements and Derivatives - Fair Value of Financial Instrument (Details) (Fair Value, Inputs, Level 2, USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value of Financial Instruments [Line Items]
Carrying Value	$ 1,585	$ 1,599
Fair Value	1,675	1,665
Market Approach Valuation Technique \| Senior Notes Total [Member]
Fair Value of Financial Instruments [Line Items]
Carrying Value	1,500	1,500
Fair Value	1,594	1,567
Income Approach Valuation Technique \| Other indebtedness [Member]
Fair Value of Financial Instruments [Line Items]
Carrying Value	85	99
Fair Value	$ 81	$ 98

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

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

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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