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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930

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)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Employee Benefit Plans - Fair Value Measurements (Details) - Pension - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Investments at Fair Value:	$ 51,114	$ 50,970	$ 55,546
Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Investments at Fair Value:	13,962	13,774
Mutual Funds \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Investments at Fair Value:	13,962	13,774
Mutual Funds \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Investments at Fair Value:	0	0
Common Collective Trusts
Defined Benefit Plan Disclosure [Line Items]
Investments at Net Asset Value:	$ 37,152	$ 37,196