Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 246,337	$ 258,825	$ 248,612
Trade accounts receivable, net	144,916	106,011	140,945
Inventories	218,164	195,757	212,293
Deferred income taxes	0	16,203	13,556
Other current assets	11,482	12,476	13,632
Total current assets	620,899	589,272	629,038
Property, plant and equipment, net	219,391	213,716	206,837
Goodwill	124,993	123,950	124,827
Intangible assets, net	24,912	27,675	30,743
Other noncurrent assets	9,344	6,696	4,412
Total assets	999,539	961,309	995,857
Trade accounts payable	27,069	21,309	26,915
Accrued liabilities	57,138	54,761	56,305
Income taxes payable	4,663	0	3,198
Accrued profit sharing trust contributions	3,693	5,799	3,173
Accrued cash profit sharing and commissions	15,626	8,502	13,695
Accrued workers’ compensation	4,154	4,593	4,458
Total current liabilities	112,343	94,964	107,744
Deferred income tax and other long-term liabilities	4,920	16,521	16,773
Total liabilities	117,263	111,485	124,517
Commitments and contingencies (see Note 7)
Common stock, at par value	484	481	493
Additional paid-in capital	243,046	238,212	229,279
Retained earnings	665,813	639,707	665,914
Treasury stock	(3,502)	0	(8,464)
Accumulated other comprehensive income (loss)	(23,565)	(28,576)	(15,882)
Total stockholders’ equity	882,276	849,824	871,340
Total liabilities and stockholders’ equity	$ 999,539	$ 961,309	$ 995,857