Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012 Y	Dec. 31, 2011 Y
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 183,961	$ 135,061
Accumulated amortization	(94,442)	(89,675)
Net carrying amount	89,519	45,386
Completed Technologies [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	63,631	36,731
Accumulated amortization	(25,000)	(22,913)
Net carrying amount	38,631	13,818
Finite-Lived Intangible Assets, Weighted-Average Useful Life	6	6
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	102,100	88,700
Accumulated amortization	(62,413)	(60,202)
Net carrying amount	39,687	28,498
Finite-Lived Intangible Assets, Weighted-Average Useful Life	9	9
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	14,440	8,340
Accumulated amortization	(5,722)	(5,270)
Net carrying amount	8,718	3,070
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	5	4
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	3,300	800
Accumulated amortization	(817)	(800)
Net carrying amount	2,483	0
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	9	4
Acquired License Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	490	490
Accumulated amortization	(490)	(490)
Net carrying amount	$ 0	$ 0
acquired license rights [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	10	10