Condensed Consolidated Statements of Cash Flows (Unaudited) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012 USD ($)	Jun. 30, 2011 USD ($)
Cash flows from operating activities:
Net income	$ 30,097	$ 35,134
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and amortization	15,808	13,575
Stock-based compensation expense	3,003	2,065
Provision for deferred income taxes	178	9,997
Net provision for doubtful accounts	1,073	699
Loss (gain) on sale of assets	104	(117)
Change in assets and liabilities:
Increase in receivables	(10,793)	(32,334)
Increase in inventories	(870)	(1,981)
Increase in other assets	(2,826)	(5,729)
(Decrease) increase in accounts payable	(8,705)	5,091
Decrease in accrued liabilities and other	(11,247)	(5,273)
Net cash provided by operating activities	15,822	21,127
Cash flows from investing activities:
Capital expenditures	(26,315)	(16,842)
Business acquisition, net of cash acquired		(25,601)
Proceeds from sale of property, plant and equipment	371	280
Net cash used in investing activities	(25,944)	(42,163)
Cash flows from financing activities:
Borrowings on lines of credit	173,846	2,256
Payments on lines of credit	(126,233)	(2,629)
Proceeds from employee stock plans	468	1,543
Purchase of treasury stock	(24,825)	(598)
Post-closing payment for business acquisition	(11,892)
Other financing activities	(53)	(22)
Net cash provided by financing activities	11,311	550
Effect of exchange rate changes on cash	2,396	1,780
Net increase (decrease) in cash and cash equivalents	3,585	(18,706)
Cash and cash equivalents at beginning of year	25,247	83,010
Cash and cash equivalents at end of period	28,832	64,304
Cash paid for:
Income taxes (net of refunds)	5,836	11,380
Interest	$ 4,106	$ 3,602