Pension Plans and Other Employee Benefits Pension Plans Fair Value (Details) (USD $)																																																																																																																																				12 Months Ended
	Dec. 31, 2012 Pension Plans, Defined Benefit [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member]	Dec. 31, 2010 Pension Plans, Defined Benefit [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Real Estate [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Real Estate [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Hedge Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Hedge Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US Equity Securities [Member] Traded Mutual Funds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US Equity Securities [Member] Traded Mutual Funds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US Equity Securities [Member] Institutional Common Collective Trust Funds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US Equity Securities [Member] Institutional Common Collective Trust Funds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] International Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] International Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] International Equity Securities [Member] Traded Mutual Funds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] International Equity Securities [Member] Traded Mutual Funds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] International Equity Securities [Member] Institutional Common Collective Trust Funds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] International Equity Securities [Member] Institutional Common Collective Trust Funds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Commodity Contract [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Commodity Contract [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fixed Income Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fixed Income Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fixed Income Funds [Member] Traded Mutual Funds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fixed Income Funds [Member] Traded Mutual Funds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fixed Income Funds [Member] Institutional Common Collective Trust Funds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fixed Income Funds [Member] Institutional Common Collective Trust Funds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US Treasury [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US Treasury [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US corporate bonds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US corporate bonds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US corporate bonds [Member] Corporate Bonds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US corporate bonds [Member] Corporate Bonds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US corporate bonds [Member] Collateralized Mortgage Obligation Securities [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US corporate bonds [Member] Collateralized Mortgage Obligation Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] US corporate bonds [Member] Asset-backed Securities [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] US corporate bonds [Member] Asset-backed Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Total	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Total	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Real Estate [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Real Estate [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Hedge Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Hedge Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] International Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] International Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Commodity Contract [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Commodity Contract [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Fixed Income Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Fixed Income Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Treasury [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Treasury [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US corporate bonds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US corporate bonds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Real Estate [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Real Estate [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Hedge Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Hedge Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] International Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] International Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Commodity Contract [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Commodity Contract [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Fixed Income Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Fixed Income Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Treasury [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Treasury [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US corporate bonds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US corporate bonds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Real Estate [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Real Estate [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Hedge Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Hedge Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Limited Partnerships Equity Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] International Equity Securities [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] International Equity Securities [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Commodity Contract [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Commodity Contract [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Fixed Income Funds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Fixed Income Funds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Treasury [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Treasury [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US corporate bonds [Member]		Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US corporate bonds [Member]		Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Equity Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Equity Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fixed Income Funds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fixed Income Funds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] US Treasury [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] US Treasury [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member]		Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member]		Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member] Corporate Bonds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member] Corporate Bonds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member] Collateralized Mortgage Obligation Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member] Collateralized Mortgage Obligation Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member] Asset-backed Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] US corporate bonds [Member] Asset-backed Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Total	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Total	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Equity Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Equity Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Fixed Income Funds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Fixed Income Funds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Treasury [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Treasury [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US corporate bonds [Member]		Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] US corporate bonds [Member]		Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 1 [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Equity Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Equity Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Fixed Income Funds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Fixed Income Funds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Treasury [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Treasury [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US corporate bonds [Member]		Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] US corporate bonds [Member]		Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 2 [Member] Foreign corporate bonds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Equity Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Equity Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Fixed Income Funds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Fixed Income Funds [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Treasury [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Treasury [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US Agency, State and Political Subdivisions Debt Securities [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US corporate bonds [Member]		Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] US corporate bonds [Member]		Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Foreign corporate bonds [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Fair Value, Inputs, Level 3 [Member] Foreign corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Plan Assets	$ 666,400,000	$ 591,100,000	$ 557,600,000	$ 43,400,000	[1]	$ 34,700,000	[1]	$ 21,600,000	[2]	$ 21,700,000	[2]	$ 169,600,000	[3]	$ 156,300,000	[3]	$ 69,700,000	$ 94,600,000	$ 99,900,000	$ 61,700,000	$ 151,200,000	[4]	$ 117,000,000	[4]	$ 36,600,000	$ 40,900,000	$ 114,600,000	$ 76,100,000	$ 37,300,000	[5]	$ 34,600,000	[5]	$ 182,100,000	[6]	$ 166,500,000	[6]	$ 35,000,000	$ 34,200,000	$ 147,100,000	$ 132,300,000	$ 4,500,000	$ 4,900,000	$ 19,600,000	$ 17,700,000	$ 28,900,000	[7]	$ 26,600,000	[7]	$ 21,500,000	$ 18,100,000	$ 5,200,000	$ 6,100,000	$ 2,200,000	$ 2,400,000	$ 2,600,000	$ 2,600,000	$ 5,600,000	$ 8,500,000	$ 660,800,000	$ 582,600,000	$ 145,800,000	$ 174,600,000	$ 0	[1]	$ 0	[1]	$ 0	[2]	$ 0	[2]	$ 69,700,000	[3]	$ 94,600,000	[3]	$ 36,600,000	[4]	$ 40,900,000	[4]	$ 0	[5]	$ 0	[5]	$ 35,000,000	[6]	$ 34,200,000	[6]	$ 4,500,000	$ 4,900,000	$ 0	$ 0	$ 0	[7]	$ 0	[7]	$ 0	$ 0	$ 455,000,000	$ 351,600,000	$ 5,000,000	[1]	$ 0	[1]	$ 0	[2]	$ 0	[2]	$ 99,900,000	[3]	$ 61,700,000	[3]	$ 114,600,000	[4]	$ 76,100,000	[4]	$ 37,300,000	[5]	$ 34,600,000	[5]	$ 147,100,000	[6]	$ 132,300,000	[6]	$ 0	$ 0	$ 19,600,000	$ 17,700,000	$ 28,900,000	[7]	$ 26,600,000	[7]	$ 2,600,000	$ 2,600,000	$ 60,000,000	$ 56,400,000	$ 38,400,000	[1]	$ 34,700,000	[1]	$ 21,600,000	[2]	$ 21,700,000	[2]		$ 0	[3]	$ 0	[3]	$ 0.0	[4]	$ 0	[4]	$ 0	[5]	$ 0	[5]	$ 0	[6]	$ 0	[6]	$ 0	$ 0	$ 0	$ 0	$ 0	[7]	$ 0	[7]	$ 0	$ 0	$ 90,300,000	$ 77,400,000	$ 65,800,000	$ 1,700,000	$ 1,400,000	$ 200,000	$ 200,000	$ 13,700,000	$ 14,300,000	$ 28,600,000	$ 27,200,000	$ 20,100,000	[8]	$ 14,800,000	[8]	$ 17,100,000	$ 12,700,000	$ 1,400,000	$ 600,000	$ 1,600,000	$ 1,500,000	$ 2,200,000	$ 1,500,000	$ 23,800,000	$ 18,000,000	$ 66,500,000	$ 59,400,000	$ 15,600,000	$ 15,900,000	$ 1,700,000	$ 1,400,000	$ 200,000	$ 200,000	$ 13,700,000	$ 14,300,000	$ 0	$ 0	$ 0	[8]	$ 0	[8]	$ 0	$ 0	$ 50,900,000	$ 43,500,000	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 28,600,000	$ 27,200,000	$ 20,100,000	[8]	$ 14,800,000	[8]	$ 2,200,000	$ 1,500,000	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	[8]	$ 0	[8]	$ 0	$ 0
Actual return on plan assets [Abstract]
Balance at beginning of period																																																																																																																																				56,400,000	38,800,000	34,700,000		30,300,000		21,700,000		8,400,000		100,000
Relating to assets still held																																																																																																																																				2,200,000	2,500,000	1,600,000		3,900,000		600,000		(1,300,000)		(100,000)
Relating to assets sold																																																																																																																																				900,000		1,300,000				(400,000)
Purchase, sales and settlements																																																																																																																																				500,000	15,100,000	800,000		500,000		(300,000)		14,600,000		0
Balance at end of period																																																																																																																																				$ 60,000,000	$ 56,400,000	$ 38,400,000		$ 34,700,000		$ 21,600,000		$ 21,700,000		$ 0

[1] (c) This category is comprised of institutional common/collective trust funds and a limited partnership valued at NAV on a quarterly basis.

[2] (g) This category is comprised of closely-held limited partnerships valued at NAV on a quarterly basis.

[3] (a) At December 31, 2012 and 2011, this category is comprised of $69.7 million and $94.6 million, respectively, of traded mutual funds valued at daily listed prices and $99.9 million and $61.7 million, respectively, of institutional common/collective trust funds valued at NAV per share.

[4] (b) At December 31, 2012 and 2011, this category is comprised of $36.6 million and $40.9 million, respectively, of traded mutual funds valued at daily listed prices and $114.6 million and $76.1 million, respectively, of institutional common/collective trust funds valued at daily NAV per share.

[5] (d) This category is comprised of institutional common/collective trust funds valued at daily NAV per share.

[6] (e) At December 31, 2012 and 2011, this category is comprised of $35.0 million and $34.2 million, respectively, of traded mutual funds valued at daily listed prices and $147.1 million and $132.3 million, respectively, of institutional common/collective trust funds valued at daily NAV per share.

[7] (f) At December 31, 2012 and 2011, this category is comprised of $21.5 million and $18.1 million, respectively, of corporate bonds, $5.2 million and $6.1 million, respectively, of collateralized mortgage obligations and $2.2 million and $2.4 million, respectively, of other asset-backed securities.

[8] (a) At December 31, 2012 and 2011, this category is comprised of $17.1 million and $12.7 million, respectively, of corporate bonds, $1.4 million and $0.6 million, respectively, of collateralized mortgage obligations and $1.6 million and $1.5 million, respectively, of other asset-backed securities.