INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income before income tax expense
U.S. operations								$ 61,353	$ 32,328	$ 63,049
Foreign operations								14,397	6,574	18,858
Income before income tax expense	24,710	17,594	12,117	2,518	13,146	13,294	9,944	75,750	38,902	81,907
Current:
Federal								20,154	6,665	18,708
State								4,472	1,903	3,347
Foreign								4,808	3,621	3,936
Total current								29,434	12,189	25,991
Deferred:
Federal								(1,315)	4,135	2,934
State								753	607	608
Foreign								293	(1,213)	851
Total deferred								(269)	3,529	4,393
Income tax expense	9,113	6,753	4,285	1,772	4,916	5,481	3,549	29,165	15,718	30,384
Deferred tax assets
Accounts receivable, principally due to allowance for doubtful accounts				2,127				2,750	2,127
Inventories				3,649				3,883	3,649
Net operating loss carryforwards				8,817				8,626	8,817
Accrued pension				3,136				27,598	3,136
Stock-based compensation				7,347				5,794	7,347
Compensation-related accruals				3,364				4,218	3,364
Warranty				2,880				2,893	2,880
Obligation for postretirement benefits other than pension				3,770				3,706	3,770
Accrued liabilities and other items				7,956				9,247	7,956
Gross deferred tax assets				43,046				68,715	43,046
Valuation allowance				(8,991)				(7,901)	(8,991)
Net deferred tax assets				34,055				60,814	34,055
Deferred tax liabilities:
Intangibles				82,837				86,464	82,837
Plant and equipment				16,245				22,685	16,245
Gross deferred tax liabilities				99,082				109,149	99,082
Net deferred tax liabilities				$ (65,027)				$ (48,335)	$ (65,027)