Contingencies (Details) - Property Lease Guarantee [Member] $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Guarantor Obligations [Line Items]
Year longest lease expires	2065
Potential amount of undiscounted payments we could be required to make in the event of non-payment	$ 475
Present value of potential payments we could be required to make in the event of non-payment	$ 400

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248

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