CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Statement of Cash Flows [Abstract]
Net earnings	$ 47,513	$ 60,670
Adjustments to reconcile net earnings to cash provided by operating activities:
Depreciation	16,137	13,977
Amortization expense (including deferred financing fees)	2,966	2,966
Inventory obsolescence	1,436	2,186
Loss on disposal of property, plant and equipment	83	4
Unrealized foreign currency losses	1,370	1,324
Stock-based compensation	7,314	7,246
Bad debt and customer claims	(1,403)	4,854
Changes in assets and liabilities:
Customer receivables	(5,789)	28,997
Inventories	(7,611)	(6,807)
Prepaid and other current assets	5,491	(1,548)
Accounts payable	9,502	(8,186)
Current and deferred income taxes	(1,388)	958
Other current liabilities	(7,250)	758
Other noncurrent assets and liabilities	(8,967)	(11,737)
Cash provided by operating activities	59,404	95,662
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures, net	(29,433)	(25,442)
Purchase of business, net of cash acquired	0	(8,389)
Cash used in investing activities	(29,433)	(33,831)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from credit facility	304,000	253,500
Repayment of credit facility	(304,000)	(280,500)
Payment of dividends	(23,000)	(21,946)
Proceeds from the issuance of common stock	576	2,847
Purchase of common stock for treasury	(10,570)	(4,503)
Contingent purchase price payment	(6,000)	(5,000)
Cash used in financing activities	(38,994)	(55,602)
Effect of exchange rate changes on cash and cash equivalents	5,002	766
Net decrease in cash and cash equivalents	(4,021)	6,995
Cash and cash equivalents at beginning of period	9,854	4,192
Cash and cash equivalents at end of period	$ 5,833	$ 11,187