INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income before income tax expense
U.S. operations	$ 67,379	$ 32,123	$ 44,199
Foreign operations	21,447	8,724	(404)
Income before income tax expense	88,826	40,847	43,795
Current:
Federal	16,794	1,488	9,151
State	3,561	1,426	1,822
Foreign	7,900	2,834	244
Total current	28,255	5,748	11,217
Deferred:
Federal	4,087	7,044	5,593
State	695	420	775
Foreign	(2,222)	(389)	(1,143)
Total deferred	2,560	7,075	5,225
Income tax expense	30,815	12,823	16,442
Deferred tax assets:
Accounts receivable, principally due to allowance for doubtful accounts	1,514	1,365
Inventories	2,762	3,344
Net operating loss carryforwards	10,957	10,784
Accrued pension	26,924	17,242
Stock-based compensation	7,343	4,883
Compensation-related accruals	3,103	3,429
Warranty	3,459	2,884
Obligation for postretirement benefits other than pension	4,467	10,270
Interest Rate Swap Agreement		1,928
Accrued liabilities and other items	4,037	4,218
Gross deferred tax assets	64,566	60,347
Valuation allowance	(9,454)	(9,378)
Net deferred tax assets	55,112	50,969
Deferred tax liabilities:
Intangibles	82,841	80,439
Plant and equipment	11,361	13,443
Gross deferred tax liabilities	94,202	93,882
Net deferred tax liabilities	$ (39,090)	$ (42,913)