Investments (Net investment income on Leveraged and Direct Financing Leases) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Leveraged Leases, Income Statement, Income from Leveraged Leases	$ 12	$ 11
Leveraged Leases, Income Statement, Income Tax Expense on Leveraged Leases	(4)	(4)
Leveraged Leases, Income (Loss)	8	7
Capital Leases, Income Statement, Direct Financing Lease Revenue	19	20
Direct Financing Leases Income Statement Tax Expense on Direct Financing Leases	(4)	(4)
Direct Financing Leases Income Statement Net Income from Direct Financing Leases	$ 15	$ 16

Direct Financing Leases investment income after tax expense

No definition available.

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- Definition

Tax Expense on Direct Financing Leases

+ References

No definition available.

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- Definition

Revenue realized in the period on direct financing leases.

+ References

No definition available.

+ Details

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- References

No definition available.

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- Definition

Pretax lease income allocated in proportionate amounts from unearned income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77888424&loc=SL77920237-209979

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77907235&loc=d3e45152-112736

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- Definition

The tax effect from the current year income from arrangements meeting the criteria for classification as a leveraged lease.

+ References

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- Definition

The total recognized during the period for income on leases meeting the criteria for classification as leveraged leases.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77888424&loc=SL77920237-209979

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77907235&loc=d3e45152-112736

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