Retirement And Employee Benefit Plans (Changes In The Plans Benefit Obligations, Fair Value Of Assets, And Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 16.0	$ 13.0	$ 14.0
Interest cost	6.0	5.0	4.0
Employer contributions	12.0
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3.0	2.0	2.0
Interest cost	1.0	1.0	1.0
Employer contributions	0.2
Change In Benefit Obligation [Member] \| Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at January 1	134.0	103.0
Service cost	16.0	13.0
Interest cost	6.0	5.0
Actuarial loss	(7.0)	21.0
Benefits paid	(11.0)	(8.0)
Benefit obligation at December 31	138.0	134.0	103.0
Change In Benefit Obligation [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at January 1	18.0	12.0
Service cost	3.0	2.0
Interest cost	1.0	1.0
Actuarial loss	(2.0)	3.0
Benefit obligation at December 31	20.0	18.0	12.0
Change In Plan Assets [Member] \| Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	108.0	99.0
Employer contributions	12.0	12.0
Benefits paid	(11.0)	(8.0)
Actual return on plan assets	(1.0)	5.0
Fair value of plan assets at December 31	108.0	108.0	$ 99.0
Funded status of plans at December 31	(30.0)	(26.0)
Change In Plan Assets [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status of plans at December 31	$ (20.0)	$ (18.0)

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)
-URI http://asc.fasb.org/extlink&oid=6504192

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Actual Return on Plan Assets (Component of Net Periodic Pension Cost)
-URI http://asc.fasb.org/extlink&oid=6504226

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Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6522206

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

+ References

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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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The increase in the fair value of plan assets from contributions made by the employer.

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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.

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No definition available.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

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The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

+ References

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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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