Pension and Other Post-Retirement Benefit Plans (Fair Value of Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 48,900	$ 44,150	$ 40,316
Real estate [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	19,561	17,181	14,557
Hedge funds and private equity [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	29,339	26,969	25,759
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	751,246	682,553	594,697
Pension Plans [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	177,709	165,236
Pension Plans [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	524,637	473,167
Pension Plans [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	48,900	44,150
Pension Plans [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	751,246	682,553
Pension Plans [Member] | Temporary cash investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Temporary cash investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Temporary cash investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Temporary cash investments [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Common trust funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Common trust funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	10,503	5,720
Pension Plans [Member] | Common trust funds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Common trust funds [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	10,503	5,720
Pension Plans [Member] | Corporate stock [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	63,313	63,396
Pension Plans [Member] | Corporate stock [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	2,123
Pension Plans [Member] | Corporate stock [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Corporate stock [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	63,313	65,519
Pension Plans [Member] | Mutual funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	107,635	96,008
Pension Plans [Member] | Mutual funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	164,230	138,846
Pension Plans [Member] | Mutual funds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Mutual funds [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	271,865	234,854
Pension Plans [Member] | Fixed income investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	6,761	5,832
Pension Plans [Member] | Fixed income investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	349,904	326,478
Pension Plans [Member] | Fixed income investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Fixed income investments [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	356,665	332,310
Pension Plans [Member] | Real estate [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Real estate [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Real estate [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	19,561	17,181
Pension Plans [Member] | Real estate [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	19,561	17,181
Pension Plans [Member] | Hedge funds and private equity [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Hedge funds and private equity [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Pension Plans [Member] | Hedge funds and private equity [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	29,339	26,969
Pension Plans [Member] | Hedge funds and private equity [Member] | Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 29,339	$ 26,969