Other Assets, Other Long-term Liabilities and Other Income (Expense), Net (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Other Assets [Abstract]
Insurance claim receivable	$ 39,309	[1]	$ 0	[1]
Deferred income tax	29,840		0
Deferred costs	11,150		11,193
Mineral reserves	3,199		3,199
Prepaid taxes	0		2,069
Deposits	997		819
Other long-term assets	1,223		1,524
Other assets	85,718		18,804
Other Long-term Liabilities [Abstract]
Acquisition related liabilities	50,624		64,655
Insurance claim payable	39,309	[1]	0	[1]
Pension liability	35,472		34,561
Employee benefit related liabilities	3,524		3,726
Mineral royalties payable	1,859		1,762
Deferred lease incentive	1,241		1,452
Subcontractor insurance program	962		1,583
Other	6,005		1,858
Other Long-term Liabilities	138,996		109,597
Other Income (Expense), Net [Abstract]
Other (expense) income, net	(1,857)		4,421		(2,280)
Interest Income [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	2,842		2,764		4,458
Amortization of Deferred Costs [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	(1,585)		(1,399)		(1,745)
Bank Fees [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	(2,090)		(1,549)		(1,618)
Adjustment of Investments to Fair Value [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	0		(4,750)		(5,742)
Realized Loss on Sale of Investments, Net [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	(2,699)		(10)		(312)
Adjustment of Acquisition Related Liabilities [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	(256)		7,296		3,333
Gain on Sale of Property Used in Operations [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	456		726		0
Miscellaneous Income (Expense), Net [Member]
Other Income (Expense), Net [Abstract]
Other (expense) income, net	$ 1,475		$ 1,343		$ (654)

[1] Insurance claims receivable and the corresponding insurance claims payable represent expected insurable loss amounts to be received from the insurance carriers and to be paid in claims respectively.