Selected Balance Sheet And Income Statement Information Selected Income Statement Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenue:
Services	$ 1,369,614	$ 1,277,795	$ 1,275,263
Products	823,049	639,250	546,818
Total revenue	2,192,663	1,917,045	1,822,081
Cost of Services and Products:
Services	999,396	916,495	897,654
Products	603,289	461,477	421,438
Unallocated expenses	81,219	72,753	65,263
Total cost of services and products	1,683,904	1,450,725	1,384,355
Gross margin:
Services	370,218	361,300	377,609
Products	219,760	177,773	125,380
Unallocated expenses	(81,219)	(72,753)	(65,263)
Gross Margin	$ 508,759	$ 466,320	$ 437,726