Fair Value Fair Value - Carrying Value and Fair Value Classified by Level (Details) - Nonrecurring - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Carrying value
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgages Held-for-sale, Fair Value Disclosure	$ 1,338	$ 1,361
Equity Securities without Readily Determinable Fair Value, Amount	135	140
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment Contracts With Fixed Maturity	5	5
Investment Contracts Without A Fixed Maturity	377	382
Long-term debt	71,781	72,709
Estimated Fair Value \| Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment Contracts With Fixed Maturity	0	0
Investment Contracts Without A Fixed Maturity	0	0
Long-term debt	72,376	71,252
Estimated Fair Value \| Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment Contracts With Fixed Maturity	0	0
Investment Contracts Without A Fixed Maturity	0	0
Long-term debt	0	0
Estimated Fair Value \| Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgages Held-for-sale, Fair Value Disclosure	1,350	1,366
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment Contracts With Fixed Maturity	5	5
Investment Contracts Without A Fixed Maturity	364	357
Long-term debt	0	0
Estimated Fair Value \| Fair Value, Inputs, Level 1, 2 and 3 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgages Held-for-sale, Fair Value Disclosure	1,350	1,366
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment Contracts With Fixed Maturity	5	5
Investment Contracts Without A Fixed Maturity	364	357
Long-term debt	$ 72,376	$ 71,252

Investment Contracts With Fixed Maturity, Fair Value Disclosure.

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- Definition

Investment Contracts Without A Fixed Maturity, Fair Value Disclosure.

+ References

No definition available.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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- Definition

Amount of investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117539-209714

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- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

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