Pension Plans (Plan Assets for Qualified Pension Plan) (Details) - USD ($) $ in Thousands		Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		$ 553,858		$ 596,733
Defined benefit plan, fair value plan assets before accrued income		551,872		594,768
Defined benefit plan, fair value of plan assets, accrued income		1,986		1,965
Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		180,739		155,571
Defined benefit plan, fair value plan assets before accrued income		180,666		155,524
Defined benefit plan, fair value of plan assets, accrued income		73		47
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		373,119		441,162
Defined benefit plan, fair value plan assets before accrued income		371,206		439,244
Defined benefit plan, fair value of plan assets, accrued income		1,913		1,918
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Defined benefit plan, fair value plan assets before accrued income		0		0
Defined benefit plan, fair value of plan assets, accrued income		0		0
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		10,201		12,063
Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		10,201		12,063
Cash and Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Cash and Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Futures Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Futures Contracts [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Futures Contracts [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Futures Contracts [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
US Government and Agency Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value	[1]	76,136		83,915
US Government and Agency Securities [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0	[1]
US Government and Agency Securities [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		76,136		83,915	[1]
US Government and Agency Securities [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value	[1]	0		0
Corporate Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		96,970	[1]	112,811
Corporate Fixed Income [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	[1]	0
Corporate Fixed Income [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		96,970	[1]	112,811
Corporate Fixed Income [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	[1]	0
Foreign Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	[1]	0
Foreign Fixed Income [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	[1]	0	[2]
Foreign Fixed Income [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	[1]	0	[2]
Foreign Fixed Income [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	[1]	0	[2]
Other Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value	[2]	1,530		2,080
Other Fixed Income [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0	[2]
Other Fixed Income [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		1,530		2,080	[2]
Other Fixed Income [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value	[2]	0		0
Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		119,312		93,659
Mutual Funds [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		119,312		93,659
Mutual Funds [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Mutual Funds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Common Trust Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		196,570		240,438
Common Trust Funds [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Common Trust Funds [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		196,570		240,438
Common Trust Funds [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Corporate Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		51,153		49,802
Corporate Stock [Member] | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		51,153		49,802
Corporate Stock [Member] | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0		0
Corporate Stock [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		$ 0		$ 0

[1] This category represents investments in debt securities issued by the U.S. Treasury, other U.S. government corporations and agencies, states and municipalities.

[2] This category primarily represents investments in commercial and residential mortgage-backed securities.