Information Concerning Guarantor And Non-Guarantor Subsidiaries (Details 2) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash and Cash Equivalents, Period Increase (Decrease) [Abstract]
Net cash (used in) provided by continuing operating activities	$ 39,650	$ 46,232
Net cash provided by (used in) discontinued operating activities	(28)	729
Net cash (used in) provided by operating activities	39,622	46,961
Purchases of property and equipment	(61,413)	(19,855)
Collection of notes receivable	2,465	4,021
Other investing activities	2,183	130
Net cash used in investing activities - continuing operations	(56,765)	(15,704)
Net cash used in investing activities - discontinued operations	0	(1,422)
Net cash used in investing activities	(56,765)	(17,126)
Repurchases of senior notes		(26,965)
Proceeds from exercise of stock option and purchase plans	4,193	1,675
Other financing activities, net	(85)	(1,272)
Net cash provided by (used in) financing activities - continuing operations	4,108	(26,562)
Net cash provided by financing activities - discontinued operations	0	0
Net cash provided by (used in) financing activities	4,108	(26,562)
Net change in cash and cash equivalents	(13,035)	3,273
Cash and cash equivalents at beginning of period	124,398	180,029
Cash and cash equivalents at end of period	111,363	183,302
Parent Company [Member]
Cash and Cash Equivalents, Period Increase (Decrease) [Abstract]
Net cash (used in) provided by continuing operating activities	(12,553)	26,351
Net cash (used in) provided by operating activities	(12,553)	26,351
Purchases of property and equipment	(2,247)	(1,540)
Other investing activities	4
Net cash used in investing activities - continuing operations	(2,243)	(1,540)
Net cash used in investing activities - discontinued operations	0
Net cash used in investing activities	(2,243)	(1,540)
Repurchases of senior notes		(26,965)
Proceeds from exercise of stock option and purchase plans	4,193	1,675
Net cash provided by (used in) financing activities - continuing operations	4,193	(25,290)
Net cash provided by financing activities - discontinued operations	0	0
Net cash provided by (used in) financing activities	4,193	(25,290)
Net change in cash and cash equivalents	(10,603)	(479)
Cash and cash equivalents at beginning of period	117,913	175,871
Cash and cash equivalents at end of period	107,310	175,392
Guarantor Subsidiaries [Member]
Cash and Cash Equivalents, Period Increase (Decrease) [Abstract]
Net cash (used in) provided by continuing operating activities	52,137	19,143
Net cash provided by (used in) discontinued operating activities	38	45
Net cash (used in) provided by operating activities	52,175	19,188
Purchases of property and equipment	(59,166)	(18,315)
Collection of notes receivable	2,465	4,021
Other investing activities	2,179	130
Net cash used in investing activities - continuing operations	(54,522)	(14,164)
Net cash used in investing activities - discontinued operations	0
Net cash used in investing activities	(54,522)	(14,164)
Other financing activities, net	(85)	(1,272)
Net cash provided by (used in) financing activities - continuing operations	(85)	(1,272)
Net cash provided by financing activities - discontinued operations	0	0
Net cash provided by (used in) financing activities	(85)	(1,272)
Net change in cash and cash equivalents	(2,432)	3,752
Cash and cash equivalents at beginning of period	6,485	4,158
Cash and cash equivalents at end of period	4,053	7,910
Non-Guarantor Subsidiaries [Member]
Cash and Cash Equivalents, Period Increase (Decrease) [Abstract]
Net cash (used in) provided by continuing operating activities	66	738
Net cash provided by (used in) discontinued operating activities	(66)	684
Net cash (used in) provided by operating activities		1,422
Net cash used in investing activities - discontinued operations		(1,422)
Net cash used in investing activities		(1,422)
Net cash provided by financing activities - discontinued operations		0
Cash and cash equivalents at beginning of period	0
Cash and cash equivalents at end of period	0
Consolidation, Eliminations [Member]
Cash and Cash Equivalents, Period Increase (Decrease) [Abstract]
Net cash (used in) provided by continuing operating activities	0
Net cash provided by (used in) discontinued operating activities	0
Net cash (used in) provided by operating activities	0
Purchases of property and equipment	0
Collection of notes receivable	0
Other investing activities	0
Net cash used in investing activities - continuing operations	0
Net cash used in investing activities - discontinued operations	0
Net cash used in investing activities	0
Other financing activities, net	0
Net cash provided by (used in) financing activities - continuing operations	0
Net cash provided by financing activities - discontinued operations	0	0
Net cash provided by (used in) financing activities	0
Net change in cash and cash equivalents	0
Cash and cash equivalents at beginning of period	0
Cash and cash equivalents at end of period	$ 0