Fair Value (Financial Instruments Carried at Other Than Fair Value) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets
Policy loans	$ 9,702	$ 9,669
Liabilities
Collateral financing arrangement	1,085	1,121
Junior subordinated debt securities	3,146	3,144
Separate account liabilities	191,347	205,001
Carrying Value
Assets
Mortgage loans	70,447	68,211
Policy loans	9,702	9,669
Other limited partnership interests		219
Other invested assets	1,204	443
Premiums, reinsurance and other receivables	4,121	4,155
Other assets	327	285
Liabilities
Policyholder account balances	114,519	114,355
Long-term debt	14,526	15,675
Collateral financing arrangement	1,085	1,121
Junior subordinated debt securities	3,146	3,144
Other liabilities	3,870	3,208
Separate account liabilities	112,708	124,011
Estimated Fair Value
Assets
Mortgage loans	71,330	69,797
Policy loans	11,318	11,512
Other limited partnership interests		216
Other invested assets	1,204	443
Premiums, reinsurance and other receivables	4,260	4,339
Other assets	327	328
Liabilities
Policyholder account balances	115,292	116,534
Long-term debt	15,392	17,773
Collateral financing arrangement	882	894
Junior subordinated debt securities	3,995	4,319
Other liabilities	4,428	3,841
Separate account liabilities	112,708	124,011
Estimated Fair Value \| Level 1
Assets
Mortgage loans	0	0
Policy loans	0	0
Other limited partnership interests		0
Other invested assets	0	0
Premiums, reinsurance and other receivables	0	0
Other assets	0	0
Liabilities
Policyholder account balances	0	0
Long-term debt	0	0
Collateral financing arrangement	0	0
Junior subordinated debt securities	0	0
Other liabilities	0	0
Separate account liabilities	0	0
Estimated Fair Value \| Level 2
Assets
Mortgage loans	0	0
Policy loans	341	336
Other limited partnership interests		0
Other invested assets	793	0
Premiums, reinsurance and other receivables	1,230	1,283
Other assets	142	189
Liabilities
Policyholder account balances	0	0
Long-term debt	15,392	17,773
Collateral financing arrangement	0	0
Junior subordinated debt securities	3,995	4,319
Other liabilities	2,205	1,496
Separate account liabilities	112,708	124,011
Estimated Fair Value \| Level 3
Assets
Mortgage loans	71,330	69,797
Policy loans	10,977	11,176
Other limited partnership interests		216
Other invested assets	411	443
Premiums, reinsurance and other receivables	3,030	3,056
Other assets	185	139
Liabilities
Policyholder account balances	115,292	116,534
Long-term debt	0	0
Collateral financing arrangement	882	894
Junior subordinated debt securities	0	0
Other liabilities	2,223	2,345
Separate account liabilities	$ 0	$ 0

Total amount of mortgage loans not valued on a recurring basis as of the balance sheet date.

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Fair value portion of other investments not otherwise specified in the taxonomy.

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The fair value portion of investments in other limited partnership interests.

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Fair value portion of the liability of policyholders for deposits held under the terms of insurance contracts.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

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Amount before allowance of loans made to policy and contract holders using their life insurance contracts' cash value or separate accounts as collateral. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums over and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Fair value portion of other assets.

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Fair value portion of other liabilities.

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Fair value portion of receivables, including, but not limited to, trade account receivables, note receivables, and loan receivables.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Amount of liability for variable contracts that meet specified criteria that are backed by assets held in separate accounts and carried at the fair value of those assets.

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