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Debt (Long-Term Debt) (Detail) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015
Debt Instrument [Line Items] |  |  |
Accrued interest |  | $ 506 | $ 394
Debt issuance costs |  | (34) | (19)
Total |  | $ 1,986 | 1,889
Long-term debt, interest rate |  | 14.00% |
6.400% Senior Notes Due 2022 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, gross | [1] | $ 266 | 266
Long-term debt, interest rate |  | 6.40% |
Long-term debt, maturity year |  | 2022 |
Initial Callable date |  | Aug. 15, 2006 |
7.000% Debentures Due 2025 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, gross |  | $ 46 | 46
Long-term debt, interest rate |  | 7.00% |
Long-term debt, maturity year |  | 2025 |
7.150% Debentures Due 2027 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, gross |  | $ 100 | 100
Long-term debt, interest rate |  | 7.15% |
Long-term debt, maturity year |  | 2027 |
6.625% Debentures Due 2028 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, gross |  | $ 141 | 141
Long-term debt, interest rate |  | 6.625% |
Long-term debt, maturity year |  | 2028 |
5.700% Senior Notes Due 2034 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term debt, gross | [2] | $ 21 | 21
Long-term debt, interest rate |  | 5.70% |
Long-term debt, maturity year |  | 2034 |
Surplus Notes Due 2033 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Surplus notes outstanding | [3] | $ 940 | $ 940
Long-term debt, maturity year |  | 2033 |
Callable date for fifth anniversary of initial callable date |  | Jan. 15, 2018 |
[1] | Callable on or after August 15, 2006 at 100.00.
[2] | Callable anytime at the greater of 100.00 or the present value of the remaining scheduled payments of principal and interest.
[3] | Contractual interest rate is based on three month LIBOR plus 11.26%. Callable on or after January 15, 2018 and every fifth anniversary thereafter at 100.

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- Definition Earliest date before maturity when the issuer can call the outstanding debt instrument for repayment or conversion to equity, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 + Details
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- Definition Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 + Details
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