Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash	$ 69,397	$ 58,801
Accounts receivable, less allowance of $1,567 in 2012 and $1,503 in 2011	75,376	70,922
Other current assets	10,669	9,994
Total current assets	155,442	139,717
Property and equipment	235,138	223,135
Less accumulated depreciation and amortization	96,531	93,267
Total property and equipment, net	138,607	129,868
Goodwill and other acquired intangibles:
Goodwill	43,332	43,332
Other acquired intangibles, net of accumulated amortization of $22,609 in 2012 and $21,462 in 2011	25,521	26,668
Total goodwill and other acquired intangibles	68,853	70,000
Other assets	1,858	1,566
Total assets	364,760	341,151
Current liabilities:
Accounts payable	16,563	12,392
Accrued expenses	23,163	20,986
Current portion of debt and capital lease obligations	521	552
Total current liabilities	40,247	33,930
Long-term debt and capital lease obligations, less current portion	228	333
Other long-term liabilities	9,470	8,860
Deferred income taxes	10,058	11,126
Shareholders' equity:
Preferred stock	0	0
Common stock, $0.01 par value: Authorized shares - 50,000,000, Issued and outstanding shares - 28,888,315 in 2012 and 28,553,286 in 2011	289	285
Additional paid-in capital	52,212	42,212
Retained earnings	252,256	244,405
Total shareholders' equity	304,757	286,902
Total liabilities and shareholders' equity	$ 364,760	$ 341,151