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

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

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Details

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Benefit Plans Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 140,164	$ 119,261
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations as a percent of toal plan assets	62.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 8,207	10,050
Actual plan asset allocations as a percent of toal plan assets	6.00%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 133,360	113,895	$ 104,953
Pension Plan [Member] \| Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 42,784	$ 38,887
Actual plan asset allocations as a percent of toal plan assets	32.00%	34.00%
Pension Plan [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 83,352	$ 66,022
Actual plan asset allocations as a percent of toal plan assets	63.00%	58.00%
Pension Plan [Member] \| Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 7,224	$ 8,986
Actual plan asset allocations as a percent of toal plan assets	5.00%	8.00%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 6,804	$ 5,366	$ 4,462
Other Postretirement Benefits Plan [Member] \| Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,710	$ 1,627
Actual plan asset allocations as a percent of toal plan assets	25.00%	30.00%
Other Postretirement Benefits Plan [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4,111	$ 2,675
Actual plan asset allocations as a percent of toal plan assets	60.00%	50.00%
Other Postretirement Benefits Plan [Member] \| Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 983	$ 1,064
Actual plan asset allocations as a percent of toal plan assets	14.00%	20.00%