Unaudited Selected Quarterly Financial Data (Summary Of Unaudited Selected Quarterly Financial Data) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Unaudited Selected Quarterly Financial Data [Abstract]
Total revenues	$ 253,641	$ 215,357	$ 224,188	$ 232,952	$ 227,028	$ 234,440	$ 255,474	$ 291,932	$ 887,495	$ 980,631	$ 1,176,427
Gross margin	92,962	85,104	99,026	109,652	95,268	103,294	91,459	83,510	386,744	373,531	333,953
Total operating expenses	62,656	45,372	81,219	248,215	70,470	62,759	67,457	45,949	437,462	246,635	205,683
Operating (loss) income	30,431	39,732	17,807	(138,563)	24,823	40,614	24,148	43,336	(50,593)	132,921	131,470
(Loss) income from continuing operations	31,309	22,055	9,180	(108,844)	17,630	30,661	18,035	26,426	(46,300)	92,752	77,600
(Loss) income from discontinued operations	20,536	(127)	(127)	(127)	(126)	(127)	360	(128)	(20,155)	21	672
Net (loss) income	$ 51,845	$ 21,928	$ 9,053	$ (108,971)	$ 17,504	$ 30,534	$ 18,395	$ 26,298	$ (26,145)	$ 92,731	$ 76,928
(Loss) income from continuing operations, Basic	$ 0.87	$ 0.61	$ 0.26	$ (3.07)	$ 0.50	$ 0.89	$ 0.53	$ 0.78	$ (1.29)	$ 2.70	$ 2.30
Income (loss) from discontinued operations, Basic	$ 0.57	$ 0.00	$ (0.01)	$ 0.00	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.56	$ 0.00	$ (0.02)
Net (loss) income	$ 1.44	$ 0.61	$ 0.25	$ (3.07)	$ 0.50	$ 0.89	$ 0.54	$ 0.78	$ (0.73)	$ 2.70	$ 2.28
(Loss) income for continuing operations, Diluted	$ 0.85	$ 0.60	$ 0.25	$ (3.07)	$ 0.48	$ 0.86	$ 0.51	$ 0.75	$ (1.29)	$ 2.60	$ 2.27
(Loss) income from discontinued operations, Diluted	$ 0.56	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.56	$ 0.00	$ (0.02)
Net (loss) income	$ 1.41	$ 0.60	$ 0.25	$ (3.07)	$ 0.48	$ 0.86	$ 0.52	$ 0.75	$ (0.73)	$ 2.60	$ 2.25