Information Concerning Guarantor and Non-Guarantor Subsidiaries (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Net cash provided by continuing operating activities	$ 13,902	$ (7,952)
Net cash provided by (used in) discontinued operating activities	13	(26)
Net cash flows provided by operating activities	13,915	(7,978)
Purchases of property and equipment	(29,734)	(37,497)
Collection of notes receivable	2,870	2,465
Other investing activities	378	1,570
Net cash used in investing activities - continuing operations	(26,486)	(33,462)
Net cash used investing activities - discontinued operations
Net cash used in investing activities	(26,486)	(33,462)
Repayments under credit facility	(15,000)
Proceeds from exercise of stock option and purchase plans	3,232	4,052
Other financing activities, net	(187)	(42)
Net cash used in financing activities - continuing operations	(11,955)	4,010
Net cash provided by financing activities - discontinued operations
Net cash used in financing activities	(11,955)	4,010
Net change in cash and cash equivalents	(24,526)	(37,430)
Cash and cash equivalents - unrestricted, beginning of period	44,388	124,398
Cash and cash equivalents - unrestricted, end of period	19,862	86,968
Issuer [Member]
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Net cash provided by continuing operating activities	(6,782)	(37,264)
Net cash flows provided by operating activities	(6,782)	(37,264)
Purchases of property and equipment	(2,912)	(1,588)
Other investing activities		4
Net cash used in investing activities - continuing operations	(2,912)	(1,584)
Net cash used investing activities - discontinued operations
Net cash used in investing activities	(2,912)	(1,584)
Repayments under credit facility	(15,000)
Proceeds from exercise of stock option and purchase plans	3,232	4,052
Net cash used in financing activities - continuing operations	(11,768)	4,052
Net cash provided by financing activities - discontinued operations
Net cash used in financing activities	(11,768)	4,052
Net change in cash and cash equivalents	(21,462)	(34,796)
Cash and cash equivalents - unrestricted, beginning of period	37,562	117,913
Cash and cash equivalents - unrestricted, end of period	16,100	83,117
Guarantor [Member]
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Net cash provided by continuing operating activities	20,697	29,248
Net cash provided by (used in) discontinued operating activities		38
Net cash flows provided by operating activities	20,697	29,286
Purchases of property and equipment	(26,822)	(35,909)
Collection of notes receivable	2,870	2,465
Other investing activities	378	1,566
Net cash used in investing activities - continuing operations	(23,574)	(31,878)
Net cash used investing activities - discontinued operations
Net cash used in investing activities	(23,574)	(31,878)
Other financing activities, net	(187)	(42)
Net cash used in financing activities - continuing operations	(187)	(42)
Net cash provided by financing activities - discontinued operations
Net cash used in financing activities	(187)	(42)
Net change in cash and cash equivalents	(3,064)	(2,634)
Cash and cash equivalents - unrestricted, beginning of period	6,826	6,485
Cash and cash equivalents - unrestricted, end of period	3,762	3,851
Non-Guarantor [Member]
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Net cash provided by continuing operating activities	(13)	64
Net cash provided by (used in) discontinued operating activities	13	(64)
Net cash used investing activities - discontinued operations
Net cash provided by financing activities - discontinued operations
Eliminations [Member]
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
Net cash used investing activities - discontinued operations
Net cash provided by financing activities - discontinued operations