Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629

Name:	us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Debt - Extinguishment (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
Debt - Extinguishment (Details) - USD ($) $ in Millions	Apr. 30, 2015	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Extinguishment of Debt [Line Items]
Loss on extinguishment of debt		$ 100	$ 0	$ 100
Loss on extinguishment of debt, after-tax		65		$ 65
Uncollateralized Debt [Member]
Extinguishment of Debt [Line Items]
Extinguishment of Debt, Amount		$ 955
Loss on extinguishment of debt	$ 100
Loss on extinguishment of debt, after-tax	$ 65