Guarantor Financial Information (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 19,988	$ 30,524	$ 25,901	$ 36,716
Accounts receivable, less allowance for doubtful accounts	171,253	181,036
Receivables from affiliates	0
Inventories	357,382	272,039
Prepaid expenses and other current assets	16,629	10,382
Total current assets	571,293	502,268
Investment in joint venture	40,731	36,460
Goodwill	70,516	69,901
Intangible assets	85,709	93,813
Other assets	20,321	21,784
Investment in subsidiaries	0
Receivables from affiliates	0
Property, plant and equipment, net	79,822	82,141
Total assets	885,165	822,323
Current liabilities
Accounts payable	133,723	116,874
Payables due to affiliates	0
Other current liabilities	49,899	35,712
Current portion of long-term debt and short-term debt	1,309	692
Total current liabilities	184,931	153,278
Long-term debt, less current portion	302,283	314,240
Payables due to affiliates	0
Deferred income taxes	33,995	25,650
Other non-current liabilities	6,191	7,252
Stockholders' equity	347,852	312,279
Total liabilities and stockholders' equity	885,165	822,323
Parent [Member]
Current assets
Cash and cash equivalents	1,929	11,534	1,483	7,629
Accounts receivable, less allowance for doubtful accounts	81,738	88,434
Receivables from affiliates	55	273
Inventories	221,144	163,776
Prepaid expenses and other current assets	18,203	18,517
Total current assets	323,069	282,534
Investment in joint venture	40,731	36,460
Goodwill	12,921	12,921
Intangible assets	35,316	38,238
Other assets	30,917	34,691
Investment in subsidiaries	249,421	243,823
Receivables from affiliates	72,686	66,878
Property, plant and equipment, net	52,476	56,266
Total assets	817,537	771,811
Current liabilities
Accounts payable	95,552	84,437
Payables due to affiliates	1,093	1,387
Other current liabilities	35,497	25,895
Current portion of long-term debt and short-term debt	292	82
Total current liabilities	132,434	111,801
Long-term debt, less current portion	298,259	303,739
Payables due to affiliates	9,716	23,727
Deferred income taxes	15,341	6,280
Other non-current liabilities	13,935	13,985
Stockholders' equity	347,852	312,279
Total liabilities and stockholders' equity	817,537	771,811
Guarantors [Member]
Current assets
Cash and cash equivalents	2,152	582	1,835	1,068
Accounts receivable, less allowance for doubtful accounts	37,250	37,487
Receivables from affiliates	1,554	3,495
Inventories	49,886	48,980
Prepaid expenses and other current assets	(3,731)	(3,331)
Total current assets	87,111	87,213
Investment in joint venture	0
Goodwill	41,556	41,556
Intangible assets	29,843	34,395
Other assets	152	237
Investment in subsidiaries	11,742	12,151
Receivables from affiliates	79,498	71,041
Property, plant and equipment, net	15,308	15,416
Total assets	265,210	262,009
Current liabilities
Accounts payable	13,573	14,826
Payables due to affiliates	55	76
Other current liabilities	4,675	4,459
Current portion of long-term debt and short-term debt	7	50
Total current liabilities	18,310	19,411
Long-term debt, less current portion	0	1
Payables due to affiliates	13,935	8,572
Deferred income taxes	19,119	19,647
Other non-current liabilities	1,537	2,324
Stockholders' equity	212,309	212,054
Total liabilities and stockholders' equity	265,210	262,009
Non-Guarantors [Member]
Current assets
Cash and cash equivalents	15,907	18,408	22,583	28,019
Accounts receivable, less allowance for doubtful accounts	52,265	55,115
Receivables from affiliates	683	146
Inventories	86,480	59,547
Prepaid expenses and other current assets	8,162	3,483
Total current assets	163,497	136,699
Investment in joint venture	0
Goodwill	16,039	15,424
Intangible assets	20,550	21,180
Other assets	6,025	2,812
Investment in subsidiaries	0
Receivables from affiliates	634	7,292
Property, plant and equipment, net	12,038	10,459
Total assets	218,783	193,866
Current liabilities
Accounts payable	24,598	17,611
Payables due to affiliates	1,144	2,451
Other current liabilities	9,727	5,358
Current portion of long-term debt and short-term debt	1,010	560
Total current liabilities	36,479	25,980
Long-term debt, less current portion	4,024	10,500
Payables due to affiliates	129,167	112,912
Deferred income taxes	(465)	(277)
Other non-current liabilities	632	567
Stockholders' equity	48,946	44,184
Total liabilities and stockholders' equity	218,783	193,866
Eliminations [Member]
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, less allowance for doubtful accounts	0
Receivables from affiliates	(2,292)	(3,914)
Inventories	(128)	(264)
Prepaid expenses and other current assets	36
Total current assets	(2,384)	(4,178)
Investment in joint venture	0
Goodwill	0
Intangible assets	0
Other assets	0
Investment in subsidiaries	(261,163)	(255,974)
Receivables from affiliates	(152,818)	(145,211)
Property, plant and equipment, net	0
Total assets	(416,365)	(405,363)
Current liabilities
Accounts payable	0
Payables due to affiliates	(2,292)	(3,914)
Other current liabilities	0
Current portion of long-term debt and short-term debt	0
Total current liabilities	(2,292)	(3,914)
Long-term debt, less current portion	0
Payables due to affiliates	(152,818)	(145,211)
Deferred income taxes	0
Other non-current liabilities	0
Stockholders' equity	(261,255)	(256,238)
Total liabilities and stockholders' equity	$ (416,365)	$ (405,363)