Fair Value - Balance Sheet Grouping (Details) - Nonrecurring - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Carrying Value
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans	$ 1,361
Equity securities	140	$ 47
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment contracts with a fixed maturity	5
Investment contracts without a fixed maturity	382
Long-term debt	72,709	25,726
Estimated Fair Value
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans	1,366
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment contracts with a fixed maturity	5
Investment contracts without a fixed maturity	357
Long-term debt	71,252	26,756
Estimated Fair Value \| Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment contracts with a fixed maturity	0
Investment contracts without a fixed maturity	0
Long-term debt	71,252	26,756
Estimated Fair Value \| Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment contracts with a fixed maturity	0
Investment contracts without a fixed maturity	0
Long-term debt	0	0
Estimated Fair Value \| Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans	1,366
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Investment contracts with a fixed maturity	5
Investment contracts without a fixed maturity	357
Long-term debt	$ 0	$ 0

Investment Contracts With Fixed Maturity, Fair Value Disclosure.

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- Definition

Investment Contracts Without A Fixed Maturity, Fair Value Disclosure.

+ References

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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=118260190&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=116654751&loc=SL75117539-209714

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- Definition

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

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