Pension And Postretirement Benefits (Summary Of Pension Plan Assets Valued Using Net Asset Value (NAV) Or Its Equivalent) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Archstone Offshore Fund, Ltd [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[1]
Other Redemption Restrictions			None	[1]
Evanston Capital Management [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[1]
Other Redemption Restrictions			None	[1]
Strategic Value Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[2]
Other Redemption Restrictions			**	[2],[3]
U.S. Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[4]
Other Redemption Restrictions			None	[4]
Redemption Notice Period			None	[4]
Non-U.S. Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[5]
Other Redemption Restrictions			None	[5]
Redemption Notice Period			None	[5]
Non-U.S. Fixed Income, Government And Corporate [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[6]
Other Redemption Restrictions			None	[6]
Redemption Notice Period			None	[6]
International Property Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[7]
Other Redemption Restrictions			None	[7]
Redemption Notice Period			None	[7]
International Balanced Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[8]
Other Redemption Restrictions			None	[8]
Redemption Notice Period			None	[8]
U.S. Government And Corporate Fixed Income [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitment			None	[9]
Other Redemption Restrictions			None	[9]
Redemption Notice Period			None	[9]
Pension Benefits [Member] | Archstone Offshore Fund, Ltd [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 28,241	[1],[10]	$ 29,664	[1],[10]
Unfunded Commitment	None	[1]
Other Redemption Restrictions	None	[1]
Redemption Frequency	12 Months	[1]	12 Months	[1]
Redemption Notice Period	90 days written	[1]	90 days written	[1]
Pension Benefits [Member] | Evanston Capital Management [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	24,055	[1],[10]	24,716	[1],[10]
Unfunded Commitment	None	[1]
Other Redemption Restrictions	None	[1]
Redemption Frequency	12 Months	[1]	12 Months	[1]
Redemption Notice Period	65 days written	[1]	60 days written	[1]
Pension Benefits [Member] | Strategic Value Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	15,671	[10],[2]	17,169	[10],[2]
Unfunded Commitment	None	[2]
Other Redemption Restrictions	None	[2]
Redemption Frequency	12 Months	[2]	12 Months	[2]
Redemption Notice Period	90 days written	[2]	90 days written	[2]
Pension Benefits [Member] | U.S. Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	26,322	[10],[4]	25,954	[10],[4]
Unfunded Commitment	None	[4]
Other Redemption Restrictions	None	[4]
Redemption Frequency	immediate	[4]	Immediate	[4]
Redemption Notice Period	None	[4]
Pension Benefits [Member] | Non-U.S. Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	198,655	[10],[4]	228,551	[10],[5]
Unfunded Commitment	None	[4]
Other Redemption Restrictions	None	[4]
Redemption Frequency	immediate	[4]	Immediate	[5]
Redemption Notice Period	None	[4]
Pension Benefits [Member] | Non-U.S. Fixed Income, Government And Corporate [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	159,611	[10],[11]	145,811	[10],[6]
Unfunded Commitment	None	[11]
Other Redemption Restrictions	None	[11]
Redemption Frequency	immediate	[11]	Immediate	[6]
Redemption Notice Period	None	[11]
Pension Benefits [Member] | International Property Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	9,011	[10],[7]	8,347	[10],[7]
Unfunded Commitment	None	[7]
Other Redemption Restrictions	None	[7]
Redemption Frequency	immediate	[7]	Immediate	[7]
Redemption Notice Period	None	[7]
Pension Benefits [Member] | International Balanced Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	8,223	[10],[8]	6,017	[10],[8]
Unfunded Commitment	None	[8]
Other Redemption Restrictions	None	[8]
Redemption Frequency	immediate	[8]	Immediate	[8]
Redemption Notice Period	None	[8]
Pension Benefits [Member] | U.S. Government And Corporate Fixed Income [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	33,810	[10],[12]	41,787	[10],[9]
Unfunded Commitment	None	[12]
Other Redemption Restrictions	None	[12]
Redemption Frequency	immediate	[12]	Immediate	[9]
Redemption Notice Period	None	[12]
Pension Benefits [Member] | US Tactical Allocation Balanced Fund [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 16,455	[10],[13]
Unfunded Commitment	None	[13]
Other Redemption Restrictions	None	[13]
Redemption Frequency	immediate	[13]
Redemption Notice Period	None	[13]

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

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

[3] This fund is an alternative investment and withdrawals are not permitted until September 2011

[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 Government and Corporate 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 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 U.S. fixed income securities, corporate, government and agency, and seek to outperform the Barclays Capital Aggregate Index

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

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

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

[13] These funds invest in global bonds, global stocks, real estate and commodities and seek to outperform U.S. inflation by 5% over a market cycle