Pensions and Other Postretirement Benefit Plans (Schedule of Fair Value of Plan Assets) (Details) - Pension Plans [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 180,672	$ 171,387	$ 183,199
Investment of plan assets	180,672	171,387
Total investments in the fair value hierarchy [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	80,397	77,194
Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,710	2,905
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74,449	71,886
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,238	2,403	2,133
Common Stocks and Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	309	404
Investment of plan assets	35,510	34,709
Common Stocks and Equity Funds [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	309	404
Common Stocks and Equity Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Common Stocks and Equity Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74,449	71,886
Debt Securities [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74,449	71,886
Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fixed income funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment of plan assets	59,662	53,616
Insurance Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,238	2,403
Insurance Contracts [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Insurance Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Insurance Contracts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,238	2,403	$ 2,133
Cash and Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,401	2,501
Cash and Short-Term Investments [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,401	2,501
Cash and Short-Term Investments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Cash and Short-Term Investments [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment of plan assets	5,065	5,676
Limited Partnerships [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		5,676
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment of plan assets	$ 38	192
Hedge Funds [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Hedge Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Hedge Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets