Employee Benefit Plans (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Plan amounts recognized in the consolidated balance sheets
Other long-term asset	$ 4,374	$ 4,405
Pension and other post-retirement liabilities	(493,721)	(258,807)
Pension Benefits [Member]
Plan amounts recognized in the consolidated balance sheets
Other long-term asset	4,374	4,405
Other current liability	(4,918)	(4,403)
Pension and other post-retirement liabilities	(487,825)	(249,302)
Amounts recognized in the consolidated balance sheets	(488,369)	(249,300)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss	999,189	741,190
Prior service credit	(37,172)	(44,142)
Amounts recognized in accumulated other comprehensive loss	962,017	697,048
Expected cash flows for pension plans and other post retirement benefit plans
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	17,084
Defined Benefit Plan, Expected Future Benefit Payments in Year One	67,528
Defined Benefit Plan, Expected Future Benefit Payments in Year Two	77,337
Defined Benefit Plan, Expected Future Benefit Payments in Year Three	82,692
Defined Benefit Plan, Expected Future Benefit Payments in Year Four	88,292
Defined Benefit Plan, Expected Future Benefit Payments in Year Five	94,378
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter	576,891
Other Postretirement Benefits [Member]
Plan amounts recognized in the consolidated balance sheets
Other long-term asset	0	0
Other current liability	(1,618)	(2,824)
Pension and other post-retirement liabilities	(5,896)	(9,505)
Amounts recognized in the consolidated balance sheets	(7,514)	(12,329)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss	14,588	20,207
Prior service credit	(9,445)	(10,737)
Amounts recognized in accumulated other comprehensive loss	5,143	9,470
Expected cash flows for pension plans and other post retirement benefit plans
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	1,618
Expected Federal Receipts in Next Fiscal Year	0
Defined Benefit Plan, Expected Future Benefit Payments in Year One	1,740
Expected Federal Receipts, Year One	(122)
Defined Benefit Plan, Expected Future Benefit Payments in Year Two	1,330
Expected Federal Receipts, Year Two	(70)
Defined Benefit Plan, Expected Future Benefit Payments in Year Three	1,158
Expected Federal Receipts, Year Three	(56)
Defined Benefit Plan, Expected Future Benefit Payments in Year Four	1,011
Expected Federal Receipts, Year Four	(53)
Defined Benefit Plan, Expected Future Benefit Payments in Year Five	829
Expected Federal Receipts, Year Five	0
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter	1,867
Expected Federal Receipts, Five Fiscal Years Thereafter	$ 0