Retirement Benefits - Schedule of Health Care Cost Trend Rates (Details) - Other postretirement benefit plans	Dec. 31, 2018
Pre-65
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	6.50%
Ultimate Cost Trend Rate	4.50%
Post-65 medical
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	5.00%
Ultimate Cost Trend Rate	4.50%
Post-65 prescription
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	8.00%
Ultimate Cost Trend Rate	4.50%

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.

No definition available.

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- Definition

Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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- Definition

Ultimate trend rate for health care cost for defined benefit postretirement plan.

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