Income Taxes (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Sources and tax effects of the differences between the benefit from income taxes and the amount computed by applying the federal statutory income tax rate to losses before provision for income taxes
Income tax benefit at the federal statutory tax rate of 35%	$ (53,809)	$ (67,272)	$ (6,727)
Income tax benefit at the federal statutory tax rate of 35%	35.00%	35.00%	35.00%
Income Tax Provision (Benefit) Resulting from
Statutory depletion	(18,931)	(20,301)	(19,464)
State and local income taxes, net of federal income tax benefit	(6,445)	3,465	1,457
Nondeductible expense	1,692	1,583	1,694
ESOP dividend deduction	(1,267)	(1,665)	(2,408)
Recapture U.S. Production Activities deduction	0	2,993	0
Fair market value over tax basis of contributions	0	(3,223)	(2,931)
Undistributed foreign earnings	(2,553)	(3,331)	(4,461)
Tax loss on sale of stock - divestiture	0	0	(4,143)
Reversal cash surrender value - COLI plans	(483)	(448)	(412)
Prior year true up adjustments	3,115	(1,095)	375
Provision (benefit) for uncertain tax positions	390	1,017	(451)
Other, net	(192)	(1,386)	(398)
Statutory depletion	12.30%	10.60%	101.30%
State and local income taxes, net of federal income tax benefit	4.20%	(1.80%)	(7.60%)
Nondeductible expense	(1.10%)	(0.80%)	(8.80%)
ESOP dividend deduction	0.80%	0.90%	12.50%
Recapture U.S. Production Activities deduction	0.00%	(1.60%)	0.00%
Fair market value over tax basis of contributions	0.00%	1.70%	15.30%
Undistributed foreign earnings	1.70%	1.70%	23.20%
Tax loss on sale of stock - divestiture	0.00%	0.00%	21.60%
Reversal cash surrender value - COLI plans	0.30%	0.20%	2.10%
Prior year true up adjustments	(2.10%)	0.60%	(2.00%)
Provision (benefit) for uncertain tax positions	(0.30%)	(0.50%)	2.30%
Other, net	0.20%	0.60%	2.10%
Total benefit from income taxes	$ (78,483)	$ (89,663)	$ (37,869)
Total income tax benefit	51.00%	46.60%	197.00%