Income Taxes: Effective tax rate (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Contingency [Line Items]
Tax Benefit from Stock Options Exercised	$ 6,966,000	$ 4,567,000	$ 4,288,000
Income (Loss) from Continuing Operations Attributable to Parent [Abstract]
Income from continuing operations, United States	48,964,000	62,204,000	63,575,000
Income from continuing operations, foreign	3,750,000	(365,000)	2,847,000
Income from continuing operations	52,714,000	61,839,000	66,422,000
Income Tax Expense (Benefit) [Abstract]
Current Federal Tax Expense (Benefit)	14,575,000	21,072,000	19,246,000
Current State and Local Tax Expense (Benefit)	2,145,000	2,080,000	1,246,000
Current Foreign Tax Expense (Benefit)	(70,000)	678,000	785,000
Current Income Tax Expense (Benefit)	16,650,000	23,830,000	21,277,000
Deferred Federal Income Tax Expense (Benefit)	164,000	(2,276,000)	169,000
Deferred State and Local Income Tax Expense (Benefit)	(996,000)	(796,000)	326,000
Deferred Foreign Income Tax Expense (Benefit)	(3,522,000)	(200,000)	(19,000)
Deferred Income Tax Expense (Benefit)	(4,354,000)	(3,272,000)	476,000
Income Tax Expense (Benefit)	12,296,000	20,558,000	21,753,000
Increase (Decrease) in Income Taxes Payable	1,300,000
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	18,450,000	21,644,000	23,247,000
Income Tax Reconciliation, State and Local Income Taxes	1,126,000	1,356,000	1,460,000
Income Tax Reconciliation, Tax Credits	(1,974,000)	(1,465,000)	(1,171,000)
Income Tax Reconciliation, Tax Exempt Income	0	(23,000)	(45,000)
Income Tax Reconciliation, Deductions, Qualified Production Activities	(403,000)	(1,559,000)	(1,508,000)
Income Tax Reconciliation, Foreign Income Tax Rate Differential	(4,903,000)	605,000	(230,000)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes	2.10%	2.20%	2.20%
Effective Income Tax Rate Reconciliation, Tax Credits	(3.70%)	(2.40%)	(1.80%)
Effective Income Tax Rate Reconciliation, Tax Exempt Income	0.00%	(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation, Deductions, Qualified Production Activities	(0.80%)	(2.50%)	(2.30%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential	(9.30%)	1.00%	(0.30%)
Effective Income Tax Rate, Continuing Operations	23.30%	33.20%	32.70%
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Net, Current	4,351,000	4,293,000
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	7,518,000	5,642,000
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(3,630,000)	(5,247,000)
Undistributed Earnings of Foreign Subsidiaries	13,900,000	13,500,000
Unrecognized Tax Benefits [Abstract]
Unrecognized Tax Benefits	4,236,000	4,978,000	4,411,000
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	391,000	156,000	494,000
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	1,353,000	490,000	764,000
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities	0	(230,000)	(392,000)
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	(436,000)	(1,158,000)	(299,000)
Unrecognized Tax Benefits	5,544,000	4,236,000	4,978,000
State income taxes [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	298,000	437,000
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(2,163,000)	(1,751,000)
Foreign Country [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	706,000	400,000
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	1,338,000	983,000
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	0	(2,301,000)
Accruals other [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	1,973,000	1,881,000
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	546,000	536,000
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(186,000)	(186,000)
Tax credits [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	276,000	441,000
Allowance for Doubtful Accounts [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	140,000	101,000
Inventory Valuation Reserve [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	958,000	1,247,000
Current deferred tax asset [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Gross, Current	4,351,000	4,507,000
Valuation allowance of deferred tax assets, current [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Valuation Allowance	0	(214,000)
Depreciation and Amortization [Member]
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	(429,000)	(458,000)
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(5,906,000)	(6,429,000)
Tax credits state [Member]
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	6,063,000	4,927,000
Non-current deferred tax asset, gross total [Member]
Deferred Tax Assets, Net, Noncurrent Classification [Abstract]
Deferred Income Taxes and Other Assets, Noncurrent	7,518,000	5,988,000
Valuation allowance of deferred tax assets, noncurrent [Member]
Deferred Tax Assets, Net, Current Classification [Abstract]
Deferred Tax Assets, Valuation Allowance	0	(346,000)
Acquired future tax deductions [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(610,000)	(515,000)
Stock-based compensation [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	5,684,000	5,581,000
Foreign currency translation adjustments [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(449,000)	354,000
Noncurrent deferred tax liability [Member]
Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liability	(3,630,000)	(5,247,000)
Allowance for Doubtful Accounts [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	4,000	(59,000)	(24,000)
Inventory Valuation Reserve [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	341,000	143,000	1,147,000
Accruals other [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	(470,000)	(2,375,000)	(464,000)
State and Local Jurisdiction [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	552,000	177,000	(7,000)
Acquired future tax deductions [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	40,000	50,000	293,000
Depreciation and Amortization [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	(3,850,000)	(700,000)	(205,000)
Tax credits [Member]
Income Tax Expense (Benefit) [Abstract]
Deferred Income Tax Expense (Benefit)	$ (971,000)	$ (508,000)	$ (264,000)