Investments (Leveraged and Direct Financing Leases - Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Investments, All Other Investments [Abstract]
Leveraged Leases, Net Investment in Leveraged Leases Disclosure, Investment in Leveraged Leases, Net	$ 803	$ 816
Direct Financing Lease, Net Investment in Lease, after Allowance for Credit Loss	1,200	1,300
Leveraged and Direct Financing Leases, Allowance for credit loss	$ 43	$ 44

Amount, after allowance for credit loss, of net investment in direct financing lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123420820&loc=SL77919306-209978

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- References

No definition available.

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- Definition

The net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 30
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=123391856&loc=d3e42840-112730

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 50
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123392319&loc=SL77920254-209983

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- Definition

Amount of allowance for credit loss on net investment in sales-type and direct financing leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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