Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income before income taxes [Abstract]
United States	$ 57,846	$ 57,651	$ 53,315
Foreign	(5,873)	(4,045)	4,927
Income before income taxes	51,973	53,606	58,242
Current provision (benefit) [Abstract]
Federal	19,758	18,713	16,239
State	2,553	2,992	2,785
Foreign	255	243	2,664
Total current provision	22,566	21,948	21,688
Deferred benefit [Abstract]
Federal	(1,183)	(1,627)	(885)
State	(275)	(222)	(923)
Foreign	(1,101)	(699)	(852)
Total deferred benefit	(2,559)	(2,548)	(2,660)
Total provision (benefit) [Abstract]
Federal	18,575	17,086	15,354
State	2,278	2,770	1,862
Foreign	(846)	(456)	1,812
Total tax provision	20,007	19,400	19,028
Reconciliation of provision for income taxes [Abstract]
Tax at the statutory federal income tax rate	18,191	18,762	20,385
Qualified production activity deduction	(1,174)	(1,360)	(1,395)
State income tax, net of federal income tax	1,386	1,727	1,105
Other permanent differences	393	840	464
Research and development tax credits	(291)	(1,323)	(2,054)
Change in valuation allowance	2,036	1,675	810
Other items	(534)	(921)	(287)
Total tax provision	20,007	19,400	19,028
Deferred tax assets [Abstract]
Inventory reserves	6,696	6,539
Warranty reserves	2,774	2,988
Bad debt reserves	409	598
State tax loss carryforwards	3,006	2,377
Accrued vacation	2,055	2,060
SERP	275	1,231
Deferred compensation	1,328	1,255
Restricted stock units	1,893	2,256
Foreign exchange gains/losses	4,549	3,111
Pension and post-employment benefits	2,232	2,197
Foreign deferred tax assets	2,773	3,311
Foreign net operating losses	5,134	3,168
Other	3,460	3,267
Valuation allowances	(8,065)	(6,029)
Total deferred tax assets	28,519	28,329
Deferred tax liabilities [Abstract]
Property and equipment	17,616	19,394
Amortization	1,019	1,087
Goodwill	1,917	2,014
Pension	1,305	1,313
Foreign tax rate differential	0	2,236
Foreign deferred tax liabilities	2,815	3,820
Total deferred tax liabilities	24,672	29,864
Total net deferred assets (liabilities)	3,847	(1,535)
Operating Loss Carryforwards [Line Items]
Recognized tax benefits related to penalties and interest settled for less than previously accrued	123	107
Unrecognized tax benefits, if recognized that would effect the effective rate	$ 618	2,722
Period company does not expect significant increase or decrease to total amount of unrecognized tax benefits	12 months
Reconciliation on unrecognized tax benefits [Roll forward]
Balance, beginning of year	$ 2,585	1,933	2,095
Additions for tax positions related to the current year	206	127	102
Additions for tax positions related to prior years	549	525	128
Reductions due to lapse of statutes of limitations	(162)	0	(149)
Decreases related to settlements with tax authorities	(2,575)	0	(243)
Balance, end of year	603	$ 2,585	$ 1,933
Breaker Technology, Ltd. [Member]
Operating Loss Carryforwards [Line Items]
Undistributed earnings of foreign subsidiaries	9,300
Telestack Limited [Member]
Operating Loss Carryforwards [Line Items]
Undistributed earnings of foreign subsidiaries	1,000
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Increase in valuation allowance on operating loss carryforwards	2,111
Increase in other deferred tax assets valuation allowance	$ (75)
Internal Revenue Service (IRS) [Member] | Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2015
Internal Revenue Service (IRS) [Member] | Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2029
U.S. Federal [Member]
Operating Loss Carryforwards [Line Items]
Period of exemption from income tax examination	2013
State [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 66,501
Tax credit carryforward	$ 864
Period of exemption from income tax examination	2008
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 16,062
Period of exemption from income tax examination	2008