Guarantees (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary of warranty accrual included in accrued liabilities
Balance at beginning of the period	$ 4,811	$ 4,186	$ 5,361
Accrual for current period warranties	8,245	4,898	991
Warranty costs incurred	(7,498)	(5,222)	(4,545)
Balance at end of the period	5,558	4,811	4,186
Acquisition of Omneon [Member]
Summary of warranty accrual included in accrued liabilities
Acquired warranty obligation	0	949
Acquisition of Scopus [Member]
Summary of warranty accrual included in accrued liabilities
Acquired warranty obligation	$ 0		$ 2,379