Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified																																																																																															12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 OPEB [Member]	Dec. 31, 2010 OPEB [Member]	Dec. 31, 2009 OPEB [Member]	Dec. 31, 2011 Pension Plan [Member]	Dec. 31, 2010 Pension Plan [Member]	Dec. 31, 2009 Pension Plan [Member]	Dec. 31, 2011 Pension Plan [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2010 Pension Plan [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2011 Pension Plan [Member] Cash and Cash Equivalents [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Cash and Cash Equivalents [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Cash and Cash Equivalents [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Cash and Cash Equivalents [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Cash and Cash Equivalents [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Cash and Cash Equivalents [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] U.S. Government Obligations [Member]	Dec. 31, 2010 Pension Plan [Member] U.S. Government Obligations [Member]	Dec. 31, 2011 Pension Plan [Member] U.S. Government Obligations [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] U.S. Government Obligations [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] U.S. Government Obligations [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] U.S. Government Obligations [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] U.S. Government Obligations [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] U.S. Government Obligations [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Corporate and Other Obligations [Member]	Dec. 31, 2010 Pension Plan [Member] Corporate and Other Obligations [Member]	Dec. 31, 2011 Pension Plan [Member] Corporate and Other Obligations [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Corporate and Other Obligations [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Corporate and Other Obligations [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Corporate and Other Obligations [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Corporate and Other Obligations [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Corporate and Other Obligations [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Common Stock [Member]	Dec. 31, 2010 Pension Plan [Member] Common Stock [Member]	Dec. 31, 2011 Pension Plan [Member] Common Stock [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Common Stock [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Common Stock [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Common Stock [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Common Stock [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Common Stock [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Commingled Funds [Member]	Dec. 31, 2010 Pension Plan [Member] Commingled Funds [Member]	Dec. 31, 2011 Pension Plan [Member] Commingled Funds [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Commingled Funds [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Commingled Funds [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Commingled Funds [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Commingled Funds [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Commingled Funds [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Common/Collective Trust Funds [Member]	Dec. 31, 2010 Pension Plan [Member] Common/Collective Trust Funds [Member]	Dec. 31, 2011 Pension Plan [Member] Common/Collective Trust Funds [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Common/Collective Trust Funds [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Common/Collective Trust Funds [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Common/Collective Trust Funds [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Common/Collective Trust Funds [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Common/Collective Trust Funds [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Registered Investment Companies [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Registered Investment Companies [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Registered Investment Companies [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Registered Investment Companies [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Registered Investment Companies [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Registered Investment Companies [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Registered Investment Companies [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Registered Investment Companies [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Limited Partnerships [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Limited Partnerships [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Limited Partnerships [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Limited Partnerships [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Limited Partnerships [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Limited Partnerships [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Interest in Limited Partnerships [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Interest in Limited Partnerships [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Insurance Contracts [Member]	Dec. 31, 2010 Pension Plan [Member] Insurance Contracts [Member]	Dec. 31, 2011 Pension Plan [Member] Insurance Contracts [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Insurance Contracts [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Insurance Contracts [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Insurance Contracts [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Insurance Contracts [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Insurance Contracts [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Pension Plan [Member] Other Investment [Member]	Dec. 31, 2010 Pension Plan [Member] Other Investment [Member]	Dec. 31, 2011 Pension Plan [Member] Other Investment [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Pension Plan [Member] Other Investment [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Pension Plan [Member] Other Investment [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Pension Plan [Member] Other Investment [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Pension Plan [Member] Other Investment [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Pension Plan [Member] Other Investment [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Interest in Limited Partnerships [Member]	Dec. 31, 2010 Interest in Limited Partnerships [Member]	Dec. 31, 2011 Commingled Funds [Member]	Dec. 31, 2010 Commingled Funds [Member]	Dec. 31, 2011 Morgan Stanley Institutional Cayman Fund LP [Member]		Dec. 31, 2011 JPM Multi-Strat II C-A Ser 11-07 [Member]		Dec. 31, 2011 RII World Timberfund, LLC [Member]		Dec. 31, 2011 MS IFHF SVP LP Cayman [Member]		Dec. 31, 2011 MS IFHF SVP LP Alpha [Member]		Dec. 31, 2011 Comm Drive, LLC [Member]		Dec. 31, 2011 CTE Drive, LLC [Member]		Dec. 31, 2011 Oakbrook Parkway LLC [Member]		Dec. 31, 2011 West Jefferson, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of OPEB plan assets			$ 5,101	$ 6,240	$ 8,028	$ 1,257,990	$ 1,290,274	$ 608,625
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of year	104,033																																																																																														42,635	29,727	37,378	13,922
Realized gains/(losses)																																																																																															1,598	(246)	12	0
Unrealized gains/(losses)																																																																																															305	1,531	(196)	2,456
Purchases and (sales), net																																																																																															59,495	11,623	0	21,000
Balance, end of year	104,033																																																																																														104,033	42,635	37,194	37,378	30,954	[1]	37,194	[2]	5,851	[3]	5,904	[1]	3,204	[1]	6,505	[4]	4,805	[4]	21,005	[4]	25,805	[4]
Fair Value	104,033																																																																																														104,033	42,635	37,194	37,378	30,954	[1]	37,194	[2]	5,851	[3]	5,904	[1]	3,204	[1]	6,505	[4]	4,805	[4]	21,005	[4]	25,805	[4]
Redemption Frequency																																																																																																			Quarterly	[1]	Quarterly	[2]	Through liquidation of underlying investments	[3]	Through liquidation of underlying investments	[1]	Through liquidation of underlying investments	[1]	Through liquidation of underlying investments	[4]	Through liquidation of underlying investments	[4]	Through liquidation of underlying investments	[4]	Through liquidation of underlying investments	[4]
Redemption Notice Period (in days)																																																																																																			60D	[1]	65D	[2]	None	[3]	None	[1]	None	[1]	None	[4]	None	[4]	None	[4]	None	[4]
Liquidation Period (in years)																																																																																																							10	[3]	2	[1]	2	[1]
Defined Benefit Plan Disclosure [Line Items]
Total investments, at fair value						1,196,140	1,136,813		335,443	329,841	719,470	726,959	141,227	80,013	34,087	46,637	0	0	34,087	46,637	0	0	120,802	144,390	0	0	120,802	144,390	0	0	323,075	262,390	0	0	323,075	262,390	0	0	251,776	226,369	251,776	226,369	0	0	0	0	99,063	107,200	0	0	61,869	69,822	37,194	37,378	8,606	38,092	0	0	8,606	38,092	0	0	253,752	268,694	83,667	103,472	170,085	165,222	0	0	104,033	42,635	0	0	0	0	104,033	42,635	805	900	0	0	805	900	0	0	141	(494)	0	0	141	(494)	0	0
Receivable for Plan Assets of Acquired Business						51,634	142,472
Receivable for Earnings on Plan Assets of Acquired Business						8,869	24,453
Interest and Dividends Receivable						2,835	2,669
Due from Broker for Securities Sold						30,085	16,780
Receivable Associated with Insurance Contract						7,727	7,400
Due to Broker for Securities Purchased						(39,300)	(40,313)
Total Plan Assets, at Fair Value			5,101	6,240	8,028	1,257,990	1,290,274	608,625
Long-term debt [Abstract]
Carrying Amount	8,205,841	7,983,614
Fair Value	$ 7,958,873	$ 8,376,515

[1] The partnership investment objective is to seek capital appreciation principally through investing in investment funds managed by third party investment managers who employ a variety of alternative investment strategies.

[2] The fund's investment objective is to generate long-term capital appreciation with relatively low volatility and a low correlation with traditional equity and fixed-income markets. The fund seeks to accomplish this objective by allocating its assets primarily among a select group of experienced portfolio managers that invest in a variety of markets, either through the medium of investment funds or through discretionary managed accounts.

[3] The partnership's objective is to realize substantial long-term capital appreciation by investing in timberland properties primarily in South America, New Zealand and Australia.

[4] The partnership invests in commercial real estate properties that are leased to the Company. The leases are triple net, whereby the Company is responsible for all expenses, including but not limited to, insurance, repairs and maintenance and payment of property taxes.