Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities
Net income	$ 43,303	$ 36,036
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on sale of assets	634	42
Depreciation and amortization	21,631	20,744
Impairment loss on assets	1,025	461
Deferred income taxes	2,336	(500)
Noncash compensation related to stock plans	9,106	7,364
Excess tax benefit of options exercised	(42)	(99)
Provision for doubtful accounts	342	470
Changes in operating assets and liabilities, net of acquisitions:
Trade accounts receivable	(36,296)	(28,630)
Inventories	17,643	14,067
Trade accounts payable	(4,543)	(381)
Income taxes payable	9,372	3,731
Accrued profit sharing trust contributions	(606)	(488)
Accrued cash profit sharing and commissions	9,053	5,458
Other current assets	(1,218)	3,686
Accrued liabilities	(112)	(791)
Long-term liabilities	(1,563)	(1,159)
Accrued workers' compensation	503	(595)
Other noncurrent assets	1,352	(2,723)
Net cash provided by operating activities	71,920	56,693
Cash flows from investing activities
Capital expenditures	(12,949)	(16,128)
Asset acquisitions, net of cash acquired	(5,300)	(56,003)
Proceeds from sale of property and equipment	1,823	6,937
Loan repayment by related parties	625	1,698
Net cash used in investing activities	(15,801)	(63,496)
Cash flows from financing activities
Repurchase of common stock	(9,825)
Debt and line of credit borrowings	1,378	2,156
Repayment of debt and line of credit borrowings	(609)	(5,655)
Debt issuance costs		(1,408)
Issuance of common stock	5,333	2,184
Excess tax benefit of options exercised	42	99
Dividends paid	(12,081)	(18,099)
Net cash used in financing activities	(15,762)	(20,723)
Effect of exchange rate changes on cash and cash equivalents	(146)	1,180
Net increase (decrease) in cash and cash equivalents	40,211	(26,346)
Cash and cash equivalents at beginning of period	175,553	213,817
Cash and cash equivalents at end of period	215,764	187,471
Noncash activity during the period
Noncash capital expenditures	670	520
Dividends declared but not paid	6,015	6,040
Issuance of Company's common stock for compensation	318	418
Non-cash contingent consideration		$ 786