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Employee Benefit Plans (Schedule of Fair Value of Other Benefits Plan Assets) (Details) - Other Benefits Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair value of plan assets	$ 36,083	$ 31,607	$ 29,018
Fair Value, Level 1 [Member]
Fair value of plan assets	24,322	18,030
Fair Value, Level 2 [Member]
Fair value of plan assets	11,761	13,577
Fair Value, Level 3 [Member]
Fair value of plan assets
Debt Securities [Member]
Fair value of plan assets		13,577
Mutual Funds [Member]
Fair value of plan assets	20,819	17,096
Mutual Funds [Member] | Fair Value, Level 1 [Member]
Fair value of plan assets	20,819	17,096
Mutual Funds [Member] | Fair Value, Level 2 [Member]
Fair value of plan assets
Mutual Funds [Member] | Fair Value, Level 3 [Member]
Fair value of plan assets
Money Market Funds [Member]
Fair value of plan assets	3,388	826
Money Market Funds [Member] | Fair Value, Level 1 [Member]
Fair value of plan assets	3,388	826
Money Market Funds [Member] | Fair Value, Level 2 [Member]
Fair value of plan assets
Money Market Funds [Member] | Fair Value, Level 3 [Member]
Fair value of plan assets
Preferred Equity Securities [Member]
Fair value of plan assets	115	108
Preferred Equity Securities [Member] | Fair Value, Level 1 [Member]
Fair value of plan assets	115	108
Preferred Equity Securities [Member] | Fair Value, Level 2 [Member]
Fair value of plan assets
Preferred Equity Securities [Member] | Fair Value, Level 3 [Member]
Fair value of plan assets
Debt Securities [Member]
Fair value of plan assets	11,761
Debt Securities [Member] | Fair Value, Level 1 [Member]
Fair value of plan assets
Debt Securities [Member] | Fair Value, Level 2 [Member]
Fair value of plan assets	11,761	13,577
Debt Securities [Member] | Fair Value, Level 3 [Member]
Fair value of plan assets

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- Definition

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

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

+ Details

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