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Employee Benefit Plans (Schedule of Change in Fair Value of Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension Benefit Plan [Member]
Change in Fair Value of Plan Assets:
Beginning Balance	$ 59,370	$ 52,931
Actual Return on Plan Assets	8,543	4,909
Employer Contributions	3,635	3,635
Benefits Paid	(2,333)	(2,105)
Ending Balance	69,215	59,370
Funded Status	(18,798)	(19,231)
Other Benefits Plan [Member]
Change in Fair Value of Plan Assets:
Beginning Balance	31,607	29,018
Actual Return on Plan Assets	3,521	1,591
Employer Contributions	1,603	1,551
Benefits Paid	(648)	(553)
Ending Balance	36,083	31,607
Funded Status	$ (18,262)	$ (17,281)

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- Definition

Change in Fair Value of Plan Assets:

+ References

No definition available.

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- Definition

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

+ 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 (b)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References

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Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

+ References

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

+ References

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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