Tax effect of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	$ 157,380	$ 41,944	$ 44,240
Net Change	115,436	(2,296)	(4,095)
Beginning Balance	41,944	44,240	48,335
Ending Balance	62,092	46,903	42,418
Net Change	15,189	4,485	13,938
Beginning Balance	46,903	42,418	28,480
Ending Balance	219,472	88,847	86,658
Net Change	130,625	2,189	9,843
Beginning Balance	88,847	86,658	76,815
Ending Balance	(848,724)	(558,325)	(424,074)
Net Change	(290,399)	(134,251)	(117,877)
Beginning Balance	(558,325)	(424,074)	(306,197)
Ending Balance	(863,379)	(573,454)	(435,437)
Net Change	(289,925)	(138,017)	(116,833)
Beginning Balance	(573,454)	(435,437)	(318,604)
Ending Balance	(643,907)	(484,607)	(348,779)
Net Change	(159,300)	(135,828)	(106,990)
Beginning Balance	(484,607)	(348,779)	(241,789)
Net Operating Loss Carryforwards
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	114,576
Net Change	114,576
Ending Balance	18,434	6,465	4,872
Net Change	11,969	1,593	4,872
Beginning Balance	6,465	4,872
Workers Compensation Allowance
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	24,004	23,290	24,624
Net Change	714	(1,334)	(1,360)
Beginning Balance	23,290	24,624	25,984
Other
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	18,800	18,654	19,616
Net Change	146	(962)	(2,735)
Beginning Balance	18,654	19,616	22,351
Ending Balance	10,670	16,031	9,485
Net Change	(5,361)	6,546	4,120
Beginning Balance	16,031	9,485	5,365
Ending Balance	(14,655)	(15,129)	(11,363)
Net Change	474	(3,766)	1,044
Beginning Balance	(15,129)	(11,363)	(12,407)
Ending Balance	(12,901)	(11,670)	(10,961)
Net Change	(1,231)	(709)	(7,091)
Beginning Balance	(11,670)	(10,961)	(3,870)
Federal benefit of foreign deferred tax liabilities
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance			9,160
Net Change		(9,160)	(256)
Beginning Balance		9,160	9,416
Federal benefit of state deferred tax liabilities
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	20,260	13,155	9,772
Net Change	7,105	3,383	2,702
Beginning Balance	13,155	9,772	7,070
Expense associated with employee stock options
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	12,728	11,252	9,129
Net Change	1,476	2,123	2,500
Beginning Balance	11,252	9,129	6,629
Property and equipment basis difference
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Ending Balance	(835,823)	(546,655)	(413,113)
Net Change	(289,168)	(133,542)	(110,786)
Beginning Balance	$ (546,655)	$ (413,113)	$ (302,327)