Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Fair Value Measurements) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Fair Value of Plan Assets, Before Payables Held Under Securities Lending Agreements			$ 350,439
Payable held under Security Lending Agreements			(4,806)	[1]
Fair Value of Plan Assets	350,588		345,633
Cash and Cash Equivalents [Member]
Cash and Equivalents	9,673		2,085
Equity Securities [Member]
U.S. Large Cap	32,304	[2]	35,099	[2]
U.S. Small Mid Cap	19,053	[3]	21,516	[3]
International Companies	34,773		9,400
Mutual Funds [Member]
Mutual Funds	185,505	[4]	124,453	[4]
Percent Invested in High-Quality Intermediate and Long-Term Investment Grade Securities	50.00%		50.00%
Percent Invested in Diversified Portfolio of Fixed-Income Instruments of Varying Maturities	50.00%		50.00%
Investments [Member]
U.S. Small Mid Cap			19,803	[5]
Developed Markets	17,401	[6]	47,916	[7]
Emerging Markets	41,300	[8]	40,983	[9]
Hedge Funds [Member]
Hedge Funds	10,579	[10]	45,693	[11]
Percent Invested in Long/Short and Event-Driven Equity	37.00%		53.00%
Percent Invested in Long and Short Credit	24.00%		11.00%
Percent in Relative Value	11.00%		14.00%
Percent Invested in Fixed Income Relative Value			5.00%
Percent Invested in Distressed Debt	10.00%		4.00%
Defined Benefit Plan, Fair Value Investments, Hedge Funds, Percent Invested in Convertible Bond Hedging	6.00%
Percent in Other Investments	12.00%		13.00%
Securities Pledged as Collateral [Member]
Money Market Funds			1,499	[12]
Mortgage-backed Securities			1,992	[13]
Level 1 [Member]
Fair Value of Plan Assets, Before Payables Held Under Securities Lending Agreements			192,553
Payable held under Security Lending Agreements			(4,806)	[1]
Fair Value of Plan Assets	281,308		187,747
Level 1 [Member] | Cash and Cash Equivalents [Member]
Cash and Equivalents	9,673		2,085
Level 1 [Member] | Equity Securities [Member]
U.S. Large Cap	32,304	[2]	35,099	[2]
U.S. Small Mid Cap	19,053	[3]	21,516	[3]
International Companies	34,773		9,400
Level 1 [Member] | Mutual Funds [Member]
Mutual Funds	185,505	[4]	124,453	[4]
Level 1 [Member] | Investments [Member]
U.S. Small Mid Cap			0	[5]
Developed Markets	0	[6]	0	[7]
Emerging Markets	0	[8]	0	[9]
Level 1 [Member] | Hedge Funds [Member]
Hedge Funds	0	[10]	0	[11]
Level 1 [Member] | Securities Pledged as Collateral [Member]
Money Market Funds			0	[12]
Mortgage-backed Securities			0	[13]
Level 2 [Member]
Fair Value of Plan Assets, Before Payables Held Under Securities Lending Agreements			112,193
Payable held under Security Lending Agreements			0	[1]
Fair Value of Plan Assets	58,701		112,193
Level 2 [Member] | Cash and Cash Equivalents [Member]
Cash and Equivalents	0		0
Level 2 [Member] | Equity Securities [Member]
U.S. Large Cap	0	[2]	0	[2]
U.S. Small Mid Cap	0	[3]	0	[3]
International Companies	0		0
Level 2 [Member] | Mutual Funds [Member]
Mutual Funds	0	[4]	0	[4]
Level 2 [Member] | Investments [Member]
U.S. Small Mid Cap			19,803	[5]
Developed Markets	17,401	[6]	47,916	[7]
Emerging Markets	41,300	[8]	40,983	[9]
Level 2 [Member] | Hedge Funds [Member]
Hedge Funds	0	[10]	0	[11]
Level 2 [Member] | Securities Pledged as Collateral [Member]
Money Market Funds			1,499	[12]
Mortgage-backed Securities			1,992	[13]
Fair Value, Inputs, Level 3 [Member]
Fair Value of Plan Assets, Before Payables Held Under Securities Lending Agreements			45,693
Payable held under Security Lending Agreements			0	[1]
Fair Value of Plan Assets	10,579		45,693
Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]
Cash and Equivalents	0		0
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
U.S. Large Cap	0	[2]	0	[2]
U.S. Small Mid Cap	0	[3]	0	[3]
International Companies	0		0
Fair Value, Inputs, Level 3 [Member] | Mutual Funds [Member]
Mutual Funds	0	[4]	0	[4]
Fair Value, Inputs, Level 3 [Member] | Investments [Member]
U.S. Small Mid Cap			0	[5]
Developed Markets	0	[6]	0	[7]
Emerging Markets	0	[8]	0	[9]
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]
Hedge Funds	10,579	[10]	45,693	[11]
Fair Value, Inputs, Level 3 [Member] | Securities Pledged as Collateral [Member]
Money Market Funds			0	[12]
Mortgage-backed Securities			$ 0	[13]

[1] 10 This category represents a payable under the securities lending agreements.

[2] 1 These are managed investments in US large cap equities that track the Russell 1000 Value index.

[3] 2 These are managed investments in US small/mid cap equities that track the Russell 2500 Growth index.

[4] 3 The mutual funds were 50% invested in high-quality intermediate and long-term investment grade securities and 50% invested in a diversified portfolio of fixed-income instruments of varying maturities, which may be represented by forwards or derivatives such as options, futures contracts or swap agreements and debt securities.

[5] 4 These are managed investments in US small/mid cap equities that track the Russell 2500 Value index.

[6] 4 These collective investments are invested in equity funds of developed markets outside of the US & Canada, that track the MSCI EAFE index.

[7] 5 These collective investments are invested in equity funds of developed markets outside of the US & Canada, that track the MSCI EAFE index.

[8] 5 These collective investments are invested in equity funds of emerging markets outside of the US & Canada, that track the MSCI Emerging Markets index.

[9] 6 These collective investments are invested in equity funds of emerging markets outside of the US & Canada, that track the MSCI Emerging Markets index.

[10] 6 The hedge funds are 37% invested in long/short and event-driven equity, 24% invested in long and short credit, 11% in relative value, 10% invested in distressed debt, 6% invested in convertible bond hedging, with the remaining 12% in other investments.

[11] 7 The hedge funds are 53% invested in long/short and event-driven equity, 11% invested in long and short credit, 14% in relative value, 5% invested in fixed income relative value, 4% invested in distressed debt, with the remaining 13% in other investments.

[12] 8 The money market holdings are invested in the Mount Vernon Securities Lending Trust Prime Portfolio.

[13] 9 The mortgage-backed securities are maintained in the U.S. Bank Illiquid Securities Liquidating Trust.