Parent Company (Guarantees) (Details) - Parent Company - USD ($) $ in Billions	Dec. 31, 2016	Dec. 31, 2015
Debt Instuments and Warrants
Condensed Financial Statement
Guarantees	$ 11.5	$ 9.1
Subsidiary Lease Obligations
Condensed Financial Statement
Guarantees	$ 1.1	$ 1.1

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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