Income Taxes (Tables)

12 Months Ended

Dec. 31, 2011

Components of the income tax provision applicable to federal, state and foreign income taxes for the years ended December 31, 2011, 2010 and 2009 are as follows (in thousands):


	2011			2010			2009
Federal income tax expense (benefit):
Current	$	16,336		$	(77,310	)	$	(117,493	)
Deferred		146,842			145,198			103,574

		163,178			67,888			(13,919	)

State income tax expense (benefit):
Current		6,056			19			(1,883	)
Deferred		13,196			3,246			(1,875	)

		19,252			3,265			(3,758	)

Foreign income tax expense (benefit):
Current		6,579			2,657			338
Deferred		(1,071	)		(954	)		(256	)

		5,508			1,703			82

Total income tax expense (benefit):
Current		28,971			(74,634	)		(119,038	)
Deferred		158,967			147,490			101,443

Total income tax expense (benefit)	$	187,938		$	72,856		$	(17,595	)

Difference Between Statutory Federal Income Tax Rate And Effective Income Tax Rate

The difference between the statutory federal income tax rate and the effective income tax rate for the years ended December 31, 2011, 2010 and 2009 is summarized as follows:


	2011			2010			2009
Statutory tax rate		35.0	%		35.0	%		35.0	%
State income taxes		2.5			1.1			4.7
Permanent differences		(0.1	)		2.3			(5.7	)
Other, net		(0.6	)		(0.2	)		0.1

Effective tax rate		36.8	%		38.2	%		34.1	%

Tax effect of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities

The tax effect of significant temporary differences representing deferred tax assets and liabilities and changes therein were as follows (in thousands):


	December 31, 2011			Net Change			December 31, 2010			Net Change			December 31, 2009			Net Change			December 31, 2008
Deferred tax assets:
Current:
Net operating loss carryforwards	$	114,576		$	114,576		$	—		$	—		$	—		$	—		$	—
Workers’ compensation allowance		24,004			714			23,290			(1,334	)		24,624			(1,360	)		25,984
Other		18,800			146			18,654			(962	)		19,616			(2,735	)		22,351

		157,380			115,436			41,944			(2,296	)		44,240			(4,095	)		48,335

Non-current:
Net operating loss carryforwards		18,434			11,969			6,465			1,593			4,872			4,872			—
Expense associated with employee stock options		12,728			1,476			11,252			2,123			9,129			2,500			6,629
Federal benefit of foreign deferred tax liabilities		—			—			—			(9,160	)		9,160			(256	)		9,416
Federal benefit of state deferred tax liabilities		20,260			7,105			13,155			3,383			9,772			2,702			7,070
Other		10,670			(5,361	)		16,031			6,546			9,485			4,120			5,365

		62,092			15,189			46,903			4,485			42,418			13,938			28,480

Total deferred tax assets		219,472			130,625			88,847			2,189			86,658			9,843			76,815

Deferred tax liabilities:
Current:
Other		(14,655	)		474			(15,129	)		(3,766	)		(11,363	)		1,044			(12,407	)

Non-current:
Property and equipment basis difference		(835,823	)		(289,168	)		(546,655	)		(133,542	)		(413,113	)		(110,786	)		(302,327	)
Other		(12,901	)		(1,231	)		(11,670	)		(709	)		(10,961	)		(7,091	)		(3,870	)

		(848,724	)		(290,399	)		(558,325	)		(134,251	)		(424,074	)		(117,877	)		(306,197	)

Total deferred tax liabilities		(863,379	)		(289,925	)		(573,454	)		(138,017	)		(435,437	)		(116,833	)		(318,604	)

Net deferred tax liability	$	(643,907	)	$	(159,300	)	$	(484,607	)	$	(135,828	)	$	(348,779	)	$	(106,990	)	$	(241,789	)