Income Taxes (Tables)

12 Months Ended

Dec. 31, 2011

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Deferred tax assets and liabilities as of December 31 are as follows:

	2011			2010
	(in thousands)
Deferred income tax assets:
Allowance for doubtful accounts	$	288		$	282
Accrued expenses	6,513			6,456
Insurance accruals	27,677			27,514
Unrealized loss on available-for-sale investments	1,078			1,078
Indirect tax benefits of unrecognized tax benefits	5,767			6,413
Other	1,276			561
Total gross deferred tax assets	42,599			42,304
Less valuation allowance	(1,078		)	(1,078		)
Net deferred tax assets	41,521			41,226
Deferred income tax liabilities:
Property and equipment	(82,897		)	(68,109		)
Goodwill	(1,195		)	(984		)
Prepaid expenses	(689		)	(650		)
	(84,781		)	(69,743		)
Net deferred tax liability	$	(43,260	)	$	(28,517	)

Summary of Deferred Tax Assets (Liabilities) by Balance Sheet Classification [Table Text Block]

The deferred tax amounts above have been classified in the accompanying consolidated balance sheets at December 31, 2011 and 2010 as follows:

	2011			2010
	(in thousands)
Current assets, net	$	14,401		$	12,400
Noncurrent liabilities, net	(57,661		)	(40,917		)
	$	(43,260	)	$	(28,517	)

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Income tax expense consists of the following:

	2011			2010			2009
	(in thousands)
Current income taxes:
Federal	$	20,460		$	40,165		$	14,369
State	2,195			(1,068		)	(4,653		)
	22,655			39,097			9,716
Deferred income taxes:
Federal	16,587			(7,804		)	14,321
State	(1,844		)	(636		)	316
	14,743			(8,440		)	14,637
Total	$	37,398		$	30,657		$	24,353

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The income tax provision differs from the amount determined by applying the U.S. federal tax rate as follows:

	2011			2010			2009
	(in thousands)
Federal tax at statutory rate (35%)	$	37,565		$	32,506		$	28,456
State taxes, net of federal benefit	981			(213		)	(1,665		)
Non-taxable interest income	(104		)	(243		)	(571		)
Uncertain income tax penalties and interest, net	(1,159		)	(1,377		)	(1,776		)
Other	115			(16		)	(91		)
	$	37,398		$	30,657		$	24,353

Reconciliation of Unrecognized Tax Benefits [Table Text Block]

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

	(in thousands)
Balance at December 31, 2010	$	18,140
Additions based on tax positions related to current year	1,200
Additions for tax positions of prior years	—
Reductions for tax positions of prior years	—
Reductions due to lapse of applicable statute of limitations	(3,278		)
Settlements	—
Balance at December 31, 2011	$	16,062