Retirement Benefits - Plan Asset Allocation (Details) (USD $) In Thousands, unless otherwise specified										12 Months Ended
	Dec. 31, 2012 Qualified Pension Benefits	Dec. 31, 2011 Qualified Pension Benefits	Dec. 31, 2010 Qualified Pension Benefits	Dec. 31, 2012 Other Benefits	Dec. 31, 2011 Other Benefits	Dec. 31, 2010 Other Benefits	Dec. 31, 2012 SERP Pension Benefits	Dec. 31, 2011 SERP Pension Benefits	Dec. 31, 2010 SERP Pension Benefits	Dec. 31, 2012 Domestic large cap equity	Dec. 31, 2012 Domestic small cap equity	Dec. 31, 2012 Non-U.S. equity	Dec. 31, 2012 Tactical asset allocation	Dec. 31, 2012 Fixed income	Dec. 31, 2012 Real estate	Dec. 31, 2012 Absolute return	Dec. 31, 2012 Cash and cash equivalents	Dec. 31, 2012 Fair Value, Measurements, Recurring Qualified Pension Benefits Level 3	Dec. 31, 2011 Fair Value, Measurements, Recurring Qualified Pension Benefits Level 3	Dec. 31, 2010 Fair Value, Measurements, Recurring Qualified Pension Benefits Level 3	Dec. 31, 2012 Fair Value, Measurements, Recurring Qualified Pension Benefits Total	Dec. 31, 2011 Fair Value, Measurements, Recurring Qualified Pension Benefits Total	Dec. 31, 2012 Fair Value, Measurements, Recurring Other Benefits Level 1	Dec. 31, 2011 Fair Value, Measurements, Recurring Other Benefits Level 1	Dec. 31, 2012 Fair Value, Measurements, Recurring Other Benefits Level 2	Dec. 31, 2011 Fair Value, Measurements, Recurring Other Benefits Level 2	Dec. 31, 2012 Fair Value, Measurements, Recurring Other Benefits Total	Dec. 31, 2011 Fair Value, Measurements, Recurring Other Benefits Total	Dec. 31, 2012 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Level 1	Dec. 31, 2011 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Level 1	Dec. 31, 2012 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Level 2	Dec. 31, 2011 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Level 2	Dec. 31, 2012 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Level 3	Dec. 31, 2011 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Level 3	Dec. 31, 2012 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Total	Dec. 31, 2011 Fair Value, Measurements, Recurring Subtotal Qualified Pension Benefits Total	Dec. 31, 2012 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Level 1	Dec. 31, 2011 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Level 1	Dec. 31, 2012 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Level 2	Dec. 31, 2011 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Level 2	Dec. 31, 2012 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Level 3	Dec. 31, 2011 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Level 3	Dec. 31, 2012 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Total	Dec. 31, 2011 Fair Value, Measurements, Recurring Equities: Qualified Pension Benefits Total	Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic large cap equity Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Domestic small cap equity Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Non-U.S. equity Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Tactical asset allocation Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Fixed income Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Absolute return Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Mutual Funds Qualified Pension Benefits Level 3	Dec. 31, 2011 Fair Value, Measurements, Recurring Mutual Funds Qualified Pension Benefits Level 3	Dec. 31, 2010 Fair Value, Measurements, Recurring Mutual Funds Qualified Pension Benefits Level 3	Dec. 31, 2012 Fair Value, Measurements, Recurring Mutual Funds Other Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Mutual Funds Other Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Mutual Funds Other Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Mutual Funds Other Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Mutual Funds Other Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Mutual Funds Other Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Level 3		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Level 3		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Qualified Pension Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Other Benefits Level 1		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Other Benefits Level 1		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Other Benefits Level 2		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Other Benefits Level 2		Dec. 31, 2012 Fair Value, Measurements, Recurring Cash and cash equivalents Other Benefits Total		Dec. 31, 2011 Fair Value, Measurements, Recurring Cash and cash equivalents Other Benefits Total		Dec. 31, 2012 Fair Value, Measurements, Recurring Net (payable) receivable Qualified Pension Benefits Total	Dec. 31, 2011 Fair Value, Measurements, Recurring Net (payable) receivable Qualified Pension Benefits Total	Dec. 31, 2012 Fair Value, Measurements, Recurring Accrued income Qualified Pension Benefits Total	Dec. 31, 2011 Fair Value, Measurements, Recurring Accrued income Qualified Pension Benefits Total
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target Allocation, Minimum										25.00%	0.00%	10.00%	0.00%	15.00%	0.00%	5.00%	0.00%
Target Allocation										32.00%	10.00%	20.00%	5.00%	23.00%	0.00%	10.00%	0.00%
Target Allocation, Maximum										40.00%	15.00%	30.00%	10.00%	30.00%	10.00%	15.00%	5.00%
Fair Value of Plan Assets	$ 531,183	$ 479,786	$ 526,469	$ 7,541	$ 7,206	$ 8,288	$ 0	$ 0	$ 0									$ 55,614	$ 45,319	$ 48,100	$ 531,183	$ 479,786	$ 7,472	$ 7,137	$ 69	$ 69	$ 7,541	$ 7,206	$ 364,914	$ 324,908	$ 110,638	$ 108,196	$ 55,615	$ 45,319	$ 531,167	$ 478,423	$ 244,975	$ 218,335	$ 78,194	$ 71,679	$ 0	$ 0	$ 323,169	$ 290,014	$ 136,994	[1]	$ 124,303	[1]	$ 28,890	[1]	$ 29,547	[1]	$ 0	[1]	$ 0	[1]	$ 165,884	[1]	$ 153,850	[1]	$ 51,264	[2]	$ 45,650	[2]	$ 0	[2]	$ 0	[2]	$ 0	[2]	$ 0	[2]	$ 51,264	[2]	$ 45,650	[2]	$ 56,717	[3]	$ 48,382	[3]	$ 49,304	[3]	$ 42,132	[3]	$ 0	[3]	$ 0	[3]	$ 106,021	[3]	$ 90,514	[3]	$ 0	[4]	$ 0	[4]	$ 26,425	[4]	$ 26,922	[4]	$ 0	[4]	$ 0	[4]	$ 26,425	[4]	$ 26,922	[4]	$ 119,939	[5]	$ 106,573	[5]	$ 0	[5]	$ 580	[5]	$ 0	[5]	$ 0	[5]	$ 119,939	[5]	$ 107,153	[5]	$ 0	[6]	$ 0	[6]	$ 0	[6]	$ 0	[6]	$ 55,615	[6]	$ 45,319	[6]	$ 55,615	[6]	$ 45,319	[6]	$ 0	$ 0	$ 12,619	$ 7,472	[7]	$ 7,137	[7]	$ 0	[7]	$ 0	[7]	$ 7,472	[7]	$ 7,137	[7]	$ 0	[8]	$ 0	[8]	$ 6,019	[8]	$ 9,015	[8]	$ 0	[8]	$ 0	[8]	$ 6,019	[8]	$ 9,015	[8]	$ 0	[9]	$ 0	[9]	$ 69	[9]	$ 69	[9]	$ 69	[9]	$ 69	[9]	$ (173)	$ 1,088	$ 189	$ 275

[1] Domestic large cap equity investments are comprised of (1) common stock, and a (2) commingled fund. Investments in common stock are valued using quoted market prices multiplied by the number of shares owned as of December 31, 2012. The investment in the commingled fund is valued at the net asset value per share multiplied by the number of shares held as of December 31, 2012.

[2] Domestic small cap equity investments are comprised of (1) common stock and a (2) mutual fund. The investments in common stock are valued using quoted market prices multiplied by the number of shares owned as of December 31, 2012. The investment in the mutual fund is valued using quoted market prices multiplied by the number of shares owned as of December 31, 2012.

[3] Non – US Equity investments are comprised of a (1) mutual fund; and a (2) commingled fund. The investment in the mutual fund is valued using quoted market prices multiplied by the number of shares owned as of December 31, 2012. The investment in the commingled fund is valued at the net asset value per share multiplied by the number of shares held as of December 31, 2012.

[4] The tactical asset allocation investment is comprised of a commingled fund, which is valued at the net asset value per share multiplied by the number of shares held as of the measurement date.

[5] Fixed income securities consist of a mutual fund. The investment in the mutual fund is valued using quoted market prices multiplied by the number of shares owned as of December 31, 2012.6 As of December 31, 2012 absolute return investments consist of two partnerships. The partnerships are valued using the fina

[6] As of December 31, 2012 absolute return investments consist of two partnerships. The partnerships are valued using the financial reports as of December 31, 2012. These investments are a Level 3 under ASC 820 because the significant valuation inputs are primarily internal to the partnerships with little third party involvement.

[7] This is a publicly traded balanced mutual fund. The fund seeks regular income, conservation of principal, and an opportunity for long-term growth of principal and income. The fair value is determined by taking the number of shares owned by the plan, and multiplying by the market price as of December 31, 2012.

[8] The investment consists of a money market fund, which is valued at the net asset value per share of $1.00 per unit as of December 31, 2012. The money market fund invests primarily in commercial paper, notes, repurchase agreements, and other evidences of indebtedness which are payable on demand or short-term in nature.

[9] This is a money market fund. The money market fund investments are valued at the net asset value per share of $1.00 per unit as of December 31, 2012. The money market fund invests primarily in commercial paper, notes, repurchase agreements, and other evidences of indebtedness which are payable on demand or short-term in nature.