INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income before income tax expense
U.S. operations	$ 31,975	$ 59,478	$ 67,379
Foreign operations	6,574	18,858	21,447
Income before income tax expense	38,549	78,336	88,826
Current:
Federal	6,360	16,766	16,794
State	1,892	3,240	3,561
Foreign	3,619	3,936	7,900
Total current:	11,871	23,942	28,255
Deferred
Federal	4,135	2,934	4,087
State	607	608	695
Foreign	(1,210)	851	(2,222)
Total deferred	3,532	4,393	2,560
Income tax expense	15,403	28,335	30,815
Deferred tax assets
Accounts receivable, principally due to allowance for doubtful accounts	2,127	1,986
Inventories	3,649	3,340
Net operating loss carryforwards	8,817	8,433
Accrued pension	3,136	31,544
Stock-based compensation	7,347	4,966
Compensation-related accruals	3,364	3,209
Warranty	2,880	2,781
Obligation for postretirement benefits other than pension	3,770	4,187
Accrued liabilities and other items	8,721	4,755
Gross deferred tax assets	43,811	65,201
Valuation allowance	(8,991)	(7,798)
Net deferred tax assets	34,820	57,403
Deferred tax liabilities:
Intangibles	82,837	84,518
Plant and equipment	16,245	11,206
Gross deferred tax liabilities	99,082	95,724
Net deferred tax liabilities	$ (64,262)	$ (38,321)