Investments (Leverage Leases - Narrative) (Details) (USD $) In Billions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Leveraged Leases [Abstract]
Deferred income tax liability related to leveraged leases	$ 1.3	$ 1.4
Percentage of rental receivables performing	100.00%	100.00%
Loans and Leases Receivable, Other Information	The payment periods for leveraged leases range from one to 15 years but in certain circumstances can be over 30 years, while the payment periods for direct financing leases range from one to 22 years.

Taxes arising from arrangements meeting the criteria for classification as leveraged leases due to timing differences between accounting and tax income recognition.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=7662751&loc=d3e45152-112736

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 35

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=7662473&loc=d3e43930-112732

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