Income Taxes (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Inventory valuation	$ 6,386,000	$ 5,468,000
Domestic net operating loss carry forwards	1,144,000	1,082,000
Tax credit carry forwards	4,145,000	3,015,000
Foreign net operating loss carry forwards		89,000
Warranty and installation accruals	2,174,000	3,044,000
Equity compensation	9,114,000	5,821,000
Other accruals	3,270,000	2,373,000
Other	760,000	1,636,000
Total deferred tax assets	26,993,000	22,528,000
Valuation allowance	(4,708,000)	(1,765,000)
Net deferred tax assets	22,285,000	20,763,000
Deferred tax liabilities:
Purchased intangible assets	9,973,000	9,818,000
Undistributed earnings	1,095,000	974,000
Depreciation	7,014,000	4,115,000
Total deferred tax liabilities	18,082,000	14,907,000
Net deferred taxes	4,203,000	5,856,000
Undistributed earnings of foreign subsidiaries	96,400,000
Increase in valuation allowance	$ 2,900,000