Property And Equipment (Schedule Of Property And Equipment Additional Information) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	$ 28,542	$ 26,686	$ 23,228
Impairment charges associated with property and equipment	162	628
Loss on asset disposals	1,961	2,383	2,088
Interest capitalized during the year	39	34	52
Cost Of Revenue [Member]
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	26,319	24,778	20,702
Selling, General, And Administrative [Member]
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	1,748	1,628	2,207
Research And Development [Member]
Property, Plant and Equipment [Line Items]
Total depreciation and amortization expense	$ 475	$ 280	$ 319