Income Taxes: Effective tax rate (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income (Loss) from Continuing Operations Attributable to Parent [Abstract]
Income from continuing operations, United States	$ 63,575,000	$ 46,669,000	$ 33,672,000
Income from continuing operations, foreign	2,847,000	1,116,000	2,935,000
Income from continuing operations	66,422,000	47,785,000	36,607,000
Income Tax Expense (Benefit) [Abstract]
Current Federal Tax Expense (Benefit)	19,246,000	15,331,000	9,533,000
Current State and Local Tax Expense (Benefit)	1,246,000	1,200,000	692,000
Current Foreign Tax Expense (Benefit)	785,000	1,109,000	1,126,000
Current Income Tax Expense (Benefit)	21,277,000	17,640,000	11,351,000
Deferred Federal Income Tax Expense (Benefit)	169,000	(781,000)	1,056,000
Deferred State and Local Income Tax Expense (Benefit)	326,000	439,000	(1,002,000)
Deferred Foreign Income Tax Expense (Benefit)	(19,000)	564,000	221,000
Deferred Income Tax Expense (Benefit)	476,000	222,000	275,000
Income Tax Expense (Benefit)	21,753,000	17,862,000	11,626,000
Tax Benefit from Stock Options Exercised	4,300,000	1,700,000	100,000
Increase (Decrease) in Income Taxes Payable	100,000
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	23,247,000	16,724,000	12,812,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%	35.00%	35.00%
Income Tax Reconciliation, State and Local Income Taxes	1,460,000	1,007,000	818,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes	2.20%	2.10%	2.20%
Income Tax Reconciliation, Tax Credits	(1,171,000)	(121,000)	(1,690,000)
Effective Income Tax Rate Reconciliation, Tax Credits	(1.80%)	(0.30%)	(4.60%)
Income Tax Reconciliation, Tax Exempt Income	(45,000)	(33,000)	(283,000)
Effective Income Tax Rate Reconciliation, Tax Exempt Income	(0.10%)	(0.10%)	(0.80%)
Income Tax Reconciliation, Deductions, Qualified Production Activities	(1,508,000)	(997,000)	(351,000)
Effective Income Tax Rate Reconciliation, Deductions, Qualified Production Activities	(2.30%)	(2.00%)	(0.90%)
Income Tax Reconciliation, Foreign Income Tax Rate Differential	(230,000)	1,282,000	320,000
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential	(0.30%)	2.70%	0.90%
Effective Income Tax Rate, Continuing Operations	32.70%	37.40%	31.80%
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	4,081,000	5,053,000
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	7,144,000	8,023,000
Deferred tax liability, Mexican subsidiary	2,600,000
Unrecognized Tax Benefits [Abstract]
Unrecognized Tax Benefits	4,411,000	5,306,000	4,887,000
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	494,000
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions		(649,000)	(29,000)
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	764,000	518,000	536,000
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities	(392,000)	(764,000)	(88,000)
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	(299,000)
Unrecognized Tax Benefits	4,978,000	4,411,000	5,306,000
Undistributed foreign subsidiaries earnings	14,000,000	10,000,000
State income taxes [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	343,000	549,000
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	0	(33,000)
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(1,481,000)	(1,661,000)
Tax credits [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	452,000	0
Tax credits state [Member]
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	4,409,000	4,597,000
Noncurrent deferred tax asset [Member]
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	4,759,000	4,564,000
Foreign Country [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	429,000	444,000
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	526,000	0
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(2,633,000)	(2,140,000)
Accruals other [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	1,377,000	1,827,000
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	347,000	0
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(186,000)	0
Depreciation and Amortization [Member]
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	(523,000)	0
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(6,862,000)	(7,193,000)
Acquired future tax deductions [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(460,000)	(28,000)
Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	3,843,000	2,943,000
Foreign currency translation [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	635,000	56,000
Noncurrent deferred tax liability [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(7,144,000)	(8,023,000)
Allowance for Doubtful Accounts [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	102,000	105,000
Inventory Valuation Reserve [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	1,378,000	2,128,000
Current deferred tax asset [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	4,081,000	5,053,000
Allowance for Doubtful Accounts [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	(24,000)	(66,000)	(17,000)
Inventory Valuation Reserve [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	1,147,000	(1,137,000)	(297,000)
Accruals other [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	(464,000)	(1,792,000)	(114,000)
State and Local Jurisdiction [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	(7,000)	(290,000)	(52,000)
Acquired future tax deductions [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	293,000	300,000	300,000
Depreciation and Amortization [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	(205,000)	2,820,000	1,571,000
Tax credits [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	$ (264,000)	$ 387,000	$ (1,116,000)