CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating Activities:
Net income	$ 47,059	$ 50,024
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization expense	27,995	24,464
Deferred income taxes	24,109	9,754
Stock-based compensation and other	7,924	8,338
Changes in assets and liabilities	(126,414)	2,047
Net cash (used in) provided by operating activities	(19,327)	94,627
Investing Activities:
Capital expenditures	(40,801)	(43,118)
Proceeds from disposition of property	25,589	0
Net cash used in investing activities	(15,212)	(43,118)
Financing Activities:
Net proceeds from issuances of common stock	2,590	1,971
Debt issuance costs	0	(3,084)
Tax benefit of stock-based compensation	253	1,161
Net cash provided by financing activities	2,843	48
Net (decrease) increase in cash and cash equivalents	(31,696)	51,557
Cash and cash equivalents, beginning of period	259,219	252,415
Cash and cash equivalents, end of period	$ 227,523	$ 303,972