Employee Benefit Plans (Accumulated Other Comprehensive Income Next Fixal Year) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Defined Benefit Plan, Expected Amortization, Next Fiscal Year [Abstract]
Actuarial loss (gain)	$ 1,763
Pension Benefits
Defined Benefit Plan, Expected Amortization, Next Fiscal Year [Abstract]
Actuarial loss (gain)	1,804
Other Postretirement Benefits
Defined Benefit Plan, Expected Amortization, Next Fiscal Year [Abstract]
Actuarial loss (gain)	$ (41)

Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position.

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

Name:	us-gaap_DefinedBenefitPlanExpectedAmortizationOfGainLossNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant