v3.8.0.1

Employee Benefit Plans (Asset Allocation Targets Reflecting a Percentage of Total Assets by Asset Class) (Details)	Dec. 31, 2017
Minimum | Pension Benefits | Equity securities | U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	2.00%
Minimum | Pension Benefits | Equity securities | International
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	2.00%
Minimum | Pension Benefits | Fixed Maturities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	48.00%
Minimum | Pension Benefits | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%
Minimum | Pension Benefits | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	2.00%
Minimum | Pension Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%
Minimum | Other Postretirement Benefits | Equity securities | U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	29.00%
Minimum | Other Postretirement Benefits | Equity securities | International
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	2.00%
Minimum | Other Postretirement Benefits | Fixed Maturities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	4.00%
Minimum | Other Postretirement Benefits | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%
Minimum | Other Postretirement Benefits | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%
Minimum | Other Postretirement Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%
Maximum | Pension Benefits | Equity securities | U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	16.00%
Maximum | Pension Benefits | Equity securities | International
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	17.00%
Maximum | Pension Benefits | Fixed Maturities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	67.00%
Maximum | Pension Benefits | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	15.00%
Maximum | Pension Benefits | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	16.00%
Maximum | Pension Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	17.00%
Maximum | Other Postretirement Benefits | Equity securities | U.S.
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	66.00%
Maximum | Other Postretirement Benefits | Equity securities | International
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	24.00%
Maximum | Other Postretirement Benefits | Fixed Maturities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	51.00%
Maximum | Other Postretirement Benefits | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	39.00%
Maximum | Other Postretirement Benefits | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%
Maximum | Other Postretirement Benefits | Other
Defined Benefit Plan Disclosure [Line Items]
Asset allocation targets	0.00%

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(i)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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