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 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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: 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

Long-Term Debt - Junior Subordinated Notes Issued to Capital Trust and Preferred Securities (Details) - USD ($) $ in Millions	Dec. 01, 2015	Dec. 31, 2015	Dec. 31, 2014
Junior subordinated notes issued to capital trusts [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0	$ 1,031
3-month LIBOR [Member] \| Junior subordinated notes issued to capital trusts [Member]
Debt Instrument [Line Items]
Basis spread on interest rate	1.926%
3-month LIBOR [Member] \| Trust Preferred Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Basis spread on interest rate	1.926%