Pension And Postretirement Benefits (Summary Of Pension Plan Assets Valued Using Net Asset Value (NAV) Or Its Equivalent) (Details) - Pension Benefits [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Archstone Offshore Fund, Ltd [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[2]	$ 34.9		$ 36.3
Redemption Frequency	[2]	12 Months		12 Months
Unfunded Commitment	[2]	None		None
Other Redemption Restrictions	[2]	None		None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]	90 days written
Evanston Capital Management [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[2]	$ 31.8		$ 30.9
Redemption Frequency	[2]	12 Months		12 Months
Unfunded Commitment	[2]	None		None
Other Redemption Restrictions	[2]	None		None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]	65 days written		60 days written
Strategic Value Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[3]	$ 0.8		$ 7.7
Redemption Frequency	[3]	12 Months		12 Months
Unfunded Commitment	[3]	None		None
Other Redemption Restrictions	[3]	None		None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]	90 days written		90 days written
Paloma International [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[4]	$ 8.0
Redemption Frequency	[4]	Quarterly
Other Redemption Restrictions	[4]	None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]	65 days written
U.S. Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 49.9		$ 100.8	[1],[4]
Redemption Frequency		immediate		immediate	[4]
Unfunded Commitment	[4]	None		None
Other Redemption Restrictions		None		None	[4]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
Graham Absolute Return [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[5]	$ 8.0
Redemption Frequency	[5]	Quarterly
Unfunded Commitment	[5]	None
Other Redemption Restrictions	[5]	None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]	30 days written
Non-U.S. Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 218.6		$ 202.6	[1],[5]
Redemption Frequency		immediate		immediate	[5]
Unfunded Commitment		None		None	[5]
Other Redemption Restrictions		None		None	[5]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
Foreign Fixed Income Government And Corporate [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 157.2		$ 177.5	[1],[6]
Redemption Frequency		immediate		immediate	[6]
Unfunded Commitment		None		None	[6]
Other Redemption Restrictions		None		None	[6]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
International Property Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 44.3		$ 53.4	[1],[7]
Redemption Frequency		immediate		immediate	[7]
Unfunded Commitment		None		None	[7]
Other Redemption Restrictions		None		None	[7]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
International Balanced Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 10.1		$ 10.1	[1],[8]
Redemption Frequency		immediate		immediate	[8]
Unfunded Commitment		None		None	[8]
Other Redemption Restrictions		None		None	[8]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
Commodities Fund [Member] [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[9]			$ 1.4
Redemption Frequency	[9]			immediate
Unfunded Commitment	[9]			None
Other Redemption Restrictions	[9]			None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]			None
Collective Trust Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[9]	$ 36.1
Redemption Frequency	[9]	immediate
Unfunded Commitment	[9]	None
Other Redemption Restrictions	[9]	None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]	None
Non-US Tactical/Alternative Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[9]	$ 18.8		$ 15.4
Redemption Frequency		immediate	[2]	immediate	[9]
Unfunded Commitment		None	[2]	None	[9]
Other Redemption Restrictions		None	[2]	None	[9]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
Commodities Fund [Member] [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 11.5		$ 11.5	[1],[10]
Redemption Frequency		immediate		immediate	[10]
Unfunded Commitment		None		None	[10]
Other Redemption Restrictions		None		None	[10]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description		None		None	[3]
Us Tactical Allocation Balanced Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	[1],[9]			$ 16.0
Redemption Frequency	[9]			immediate
Unfunded Commitment	[9]			None
Other Redemption Restrictions	[9]			None
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Description	[3]			None

[1] The fair values of the investments have been estimated using the net asset value of the investment

[2] These funds are alternative assets which seeks to outperform equities while maintaining a lower risk profile than equities.

[3] This fund is an alternative investment that invests in distressed debt instruments seeking price appreciation.

[4] These funds invest in U.S. equity securities and seeks to meet or exceed relative benchmarks

[5] These funds invest in equity securities outside the U.S. and seek to meet or exceed relative benchmarks.

[6] These funds invest in Corporate and Governments fixed income securities outside the U.S. and seek to meet or exceed relative benchmarks.

[7] These funds invest in real property outside the U.S.

[8] These funds invest in a pre defined mix of non-U.S. equity and non-U.S. fixed income securities and seek to meet or exceed the performance of a passive/local benchmark of similar mixes.

[9] These funds invest in a blend of equities, fixed income, cash and property in the U.S. and seek to outperform a similarly weighted index.

[10] These funds invest in U.S. fixed income securities, corporate, government and agency, and seek to outperform the Barclays Capital Aggregate Index.