Pension and Other Postretirement Benefits (Details 9) (Defined benefit pension plans [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 452,687	$ 453,578	$ 387,553
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	172,875	181,045
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	277,692	270,754
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,120	1,779
Cash and short-term investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	10,805	18,885
Cash and short-term investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	10,805	18,885
Cash and short-term investments [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Cash and short-term investments [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, U.S. large-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	137,051	131,749
Equity Securities, U.S. large-cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	65,484	61,257
Equity Securities, U.S. large-cap [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	71,567	70,492
Equity Securities, U.S. large-cap [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, U.S. mid-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	48,614	47,276
Equity Securities, U.S. mid-cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	48,614	47,276
Equity Securities, U.S. mid-cap [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, U.S. mid-cap [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, U.S. small-cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	47,972	53,627
Equity Securities, U.S. small-cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	47,972	53,627
Equity Securities, U.S. small-cap [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, U.S. small-cap [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	71,451	80,479
Equity Securities, International equities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Equity Securities, International equities [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	71,451	80,479
Equity Securities, International equities [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. bond funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	79,810	65,740
U.S. bond funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. bond funds [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	79,810	65,740
U.S. bond funds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
International bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	35,949	37,357
International bonds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
International bonds [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	35,949	37,357
International bonds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Real estate securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	18,915	16,686
Real estate securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Real estate securities [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	18,915	16,686
Real estate securities [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,120	1,779
Other [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Other [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Other [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 2,120	$ 1,779