Long-Term Debt (Details Textuals) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Junior Subordinated Debentures	$ 280	$ 280
Junior Subordinated Debentures 6.5% due in 2061 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	6.50%
Subordinated Debt [Member]
Debt Instrument [Line Items]
Junior Subordinated Debentures	$ 200	$ 0
Junior Subordinated Debentures 5.25% due 2062 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End	5.25%

The effective interest rate at the end of the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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(a)(1))

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

Name:	us-gaap_DebtInstrumentInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant