Pension Benefits Fair Value of Plan Assets in Heirarchy (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended									12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 investment Purchases [Member]	Dec. 31, 2012 Investment Income [Member]	Dec. 31, 2012 Cash And Money Market Funds [Member]	Dec. 31, 2011 Cash And Money Market Funds [Member]	Dec. 31, 2012 Cash And Money Market Funds [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Cash And Money Market Funds [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Cash And Money Market Funds [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Cash And Money Market Funds [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Cash And Money Market Funds [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Cash And Money Market Funds [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Domestic Equity Securities [Member]		Dec. 31, 2011 Domestic Equity Securities [Member]		Dec. 31, 2012 Domestic Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2011 Domestic Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Domestic Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2011 Domestic Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Domestic Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2011 Domestic Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 International Equity Securities [Member]		Dec. 31, 2011 International Equity Securities [Member]		Dec. 31, 2012 International Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2011 International Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 International Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2011 International Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 International Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2011 International Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Equity Securities [Member]	Dec. 31, 2011 Equity Securities [Member]		Dec. 31, 2012 Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Equity Securities [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Equity Securities [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Equity Securities [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2011 Intermediate Term Bonds [Member]		Dec. 31, 2011 Intermediate Term Bonds [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2011 Intermediate Term Bonds [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2011 Intermediate Term Bonds [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 High-yield Bonds [Member]		Dec. 31, 2012 High-yield Bonds [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 High-yield Bonds [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 High-yield Bonds [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Fixed Income Funds [Member]		Dec. 31, 2012 Fixed Income Funds [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Fixed Income Funds [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Fixed Income Funds [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Floating Rate Corporate Debt [Member]		Dec. 31, 2012 Floating Rate Corporate Debt [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Floating Rate Corporate Debt [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Floating Rate Corporate Debt [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Debt Securities [Member]	Dec. 31, 2011 Debt Securities [Member]	Dec. 31, 2012 Debt Securities [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Debt Securities [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Debt Securities [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Commodities Investment [Member]		Dec. 31, 2012 Commodities Investment [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Commodities Investment [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Commodities Investment [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Real Estate Investment [Member]		Dec. 31, 2012 Real Estate Investment [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Real Estate Investment [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Real Estate Investment [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Hedge Funds [Member]		Dec. 31, 2012 Hedge Funds [Member] Fair Value, Inputs, Level 1 [Member]		Dec. 31, 2012 Hedge Funds [Member] Fair Value, Inputs, Level 2 [Member]		Dec. 31, 2012 Hedge Funds [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2012 Other Investments [Member]	Dec. 31, 2012 Other Investments [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Other Investments [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Other Investments [Member] Fair Value, Inputs, Level 3 [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 0	$ 2,384
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3										2,329	55
Defined Benefit Plan, Fair Value of Plan Assets	$ 13,940	$ 20,254	$ 10,332	$ 17,870	$ 13,940	$ 0	$ 0	$ 2,384	$ 0			$ 778	$ 66	$ 778	$ 66	$ 0	$ 0	$ 0	$ 0	$ 5,920	[1]	$ 6,568	[2],[3]	$ 5,920	[1]	$ 6,568	[2],[3]	$ 0	[1]	$ 0	[2],[3]	$ 0	[1]	$ 0	[2],[3]	$ 2,740	[4]	$ 2,048	[3],[5]	$ 2,740	[4]	$ 2,048	[3],[5]	$ 0	[4]	$ 0	[3],[5]	$ 0	[4]	$ 0	[3],[5]	$ 8,660	$ 8,616	[3]	$ 8,660	$ 8,616	[3]	$ 0	$ 0	[3]	$ 0	$ 0	[3]	$ 5,258	[6]	$ 5,258	[6]	$ 0	[6]	$ 0	[6]	$ 1,240	[7]	$ 1,240	[7]	$ 0	[7]	$ 0	[7]	$ 4,204	[8]	$ 4,204	[8]	$ 0	[8]	$ 0	[8]	$ 1,186	[9]	$ 1,186	[8]	$ 0	[8]	$ 0	[8]	$ 6,630		$ 6,630	$ 0	$ 0	$ 669	[10]	$ 669	[10]	$ 0	[10]	$ 0	[10]	$ 783	[11]	$ 0	[11]	$ 0	[11]	$ 783	[11]	$ 2,734	[12]	$ 1,133	[12]	$ 0	[12]	$ 1,601	[12]	$ 4,186	$ 1,802	$ 0	$ 2,384
Defined Benefit Plan, Asset Allocation	100.00%	100.00%										3.80%	0.50%							29.20%	[1]	47.10%	[2],[3]													13.50%	[4]	14.70%	[3],[5]													42.70%	61.80%	[3]										37.70%	[6]							6.10%	[7]							20.80%	[8]							5.90%	[9]							32.80%	37.70%				3.30%	[10]							3.90%	[11]							13.50%	[12]							20.70%
Defined Benefit Plan, Investment Threshold, Bonds	80.00%

[1] Equity securities of United States large and small capitalization companies, which are actively traded securities that can be sold upon demand.

[2] United States equities are invested in companies that trade on active exchanges within the United States and are well diversified by industry sector and equity style, such as growth and value strategies, and passive management strategies are employed.

[3] Certain amounts have been reclassified to conform to current-year presentation.

[4] International equity securities consists of a well-diversified portfolio of holdings of mostly large issuers organized in developed countries with liquid markets, commingled with investments in equity securities of issuers located in emerging markets and believed to have strong sustainable financial productivity at attractive valuations.

[5] International equities are invested in companies that trade on active exchanges outside the United States and are well diversified among more developed markets. Active and passive strategies are employed.

[6] Intermediate term bonds seek total return. At least 80% of this fund is invested in a diversified portfolio of bonds, which include all types of securities. It invests primarily in bonds of corporate and governmental issues located in the United States and foreign countries, including emerging markets, all of which trade on active exchanges.

[7] High-yield bonds consist of non-investment grade fixed income securities. The investment objective is to obtain high current income. Due to the increased level of default risk, security selection focuses on credit-risk analysis.

[8] The objective is to achieve value added from sector or issue selection by constructing a portfolio to approximate the investment results of the Barclay's Capital Aggregate Bond Index with a modest amount of variability in duration around the index.

[9] Investments consist of floating rate bank loans. The interest rates on these loans are typically reset on a periodic basis to account for changes in the level of interest rates.

[10] Investments with exposure to commodity price movements, primarily through the use of futures, swaps and other commodity-linked securities.

[11] The investment objective of direct real estate is to provide current income with the potential for long-term capital appreciation. Ownership in real estate entails a long-term time horizon, periodic valuations, and potentially low liquidity.

[12] The hedge fund portfolio includes an investment in an actively traded global mutual fund that focuses on alternative investments and a hedge fund of funds that invests both long and short using a variety of investment strategies.