Employee Benefit Plans Employee Benefit Plans 7 (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee benefit plans
Fair Value	$ 173,648	$ 150,872	$ 142,174
Unfunded Commitments	0	0
Cash equivalents
Employee benefit plans
Fair Value	489	500
Unfunded Commitments	0	0
Fixed income fund
Employee benefit plans
Fair Value	66,669	57,674
Unfunded Commitments	0	0
U.S. small/mid cap funds
Employee benefit plans
Fair Value	26,998	24,312
Unfunded Commitments	0	0
U.S. large cap funds
Employee benefit plans
Fair Value	53,985	46,175
Unfunded Commitments	0	0
International funds
Employee benefit plans
Fair Value	17,893	14,869
Unfunded Commitments	0	0
Total equity funds
Employee benefit plans
Fair Value	98,876	85,356
Unfunded Commitments	0
Real estate funds
Employee benefit plans
Fair Value	7,614	7,342
Unfunded Commitments	$ 0	$ 0

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No definition available.

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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

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- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258

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