Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended											9 Months Ended			0 Months Ended	3 Months Ended	9 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 8.875% Senior Notes due 2017	Dec. 31, 2011 8.875% Senior Notes due 2017	Sep. 30, 2012 9.875% Senior Notes due 2020	Dec. 31, 2011 9.875% Senior Notes due 2020	Sep. 30, 2012 8.25% Senior Notes due 2021	Dec. 31, 2011 8.25% Senior Notes due 2021	Sep. 30, 2012 7.625% Senior Notes due 2022	Dec. 31, 2011 7.625% Senior Notes due 2022	Sep. 30, 2012 Senior Notes 8.875% Senior Notes due 2017	Sep. 30, 2012 Senior Notes 9.875% Senior Notes due 2020	Sep. 30, 2012 Senior Notes 8.25% Senior Notes due 2021	Nov. 02, 2012 Senior Notes 7.625% Senior Notes due 2022	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022	May 02, 2012 Senior Notes 7.625% Senior Notes due 2022	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022 Beginning in 2017	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022 Beginning in 2018	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022 Beginning in 2019	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022 Beginning in 2020	Sep. 30, 2012 Senior Notes 7.625% Senior Notes due 2022 Prior To May 15, 2015	Sep. 30, 2012 Mortgages	Sep. 30, 2012 Secured Debt
Debt Instrument [Line Items]
Senior Notes						$ 0	$ 323,342	$ 293,908	$ 293,559	$ 400,000	$ 400,000	$ 400,000	$ 0
Senior secured revolving credit facility	118,000		118,000		0
Real estate mortgage notes payable	12,711		12,711		12,116
Installment notes payable	5,800		5,800		5,546
Capital lease obligations	0		0		10
Total long-term debt and capital lease obligations	1,230,419		1,230,419		1,034,573
Current maturities of long-term debt and capital leases	4,027		4,027		3,078
Long-term debt, less current maturities	1,226,392		1,226,392		1,031,495
Unaccreted discount on Senior Notes						0	1,658	6,211	6,441
Aggregate principal amount of Senior Notes issued																		400,000	400,000
Debt issuance costs																			8,778
Amortization of debt issuance costs																		134	226
Unamortized debt issuance costs																		8,552	8,552
Senior Notes, redemption price																					103.813%	102.542%	101.271%	100.00%
Senior Notes, percentage redeemable with proceeds of equity offering																									35.00%
Senior Notes, redemption price with proceeds of equity offering																									107.625%
Stated interest rates
Senior Notes, stated interest rate														8.875%	9.875%	8.25%		7.625%	7.625%
Additional amount borrowed																	150,000
Other secured debt, minimum stated interest rate																										3.50%	2.00%
Other secured debt, maximum stated interest rate																										5.46%	9.25%
Senior Notes, registration payment arrangement
Days from closing to Target Registration Date																				270 days
Liquidated damages, percentage per annum, first 90 days after Target Registration Date																		0.25%	0.25%
Days to liquidated damages rate increase																		90 days	90 days
Increase in liquidated damages rate for each 90-day period after Target Registration Date																		0.25%	0.25%
Liquidated damages, maximum percentage per annum																		1.00%	1.00%
Loss on extinguishment of debt
Loss on extinguishment of debt	18	0	21,714	20,576										21,714
Payments of debt extinguishment costs			15,827	15,085
Write off of deferred financing costs and unaccreted discount														$ 5,887