SUPPLEMENTAL CASH FLOW FINANCIAL INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash paid during the period for:
Interest	$ 27,362	$ 27,799	$ 27,758
Income taxes	34,468	17,152	14,120
Non-cash financing and investing activities:
Purchase of property, plant and equipment in accounts payable	1,525	810	2,660
Unrealized loss on SERP (net of tax)	734	906	278
Capital lease obligations	4,615	23	157
Unrealized gain (loss) on interest rate swaps			1,514
Earnouts payable on acquisitions	2,672	4,098	2,182
Issuance of notes in connection with acquisitions	21,895	6,700	2,950
Issuance of restricted stock units of common stock	$ 5,996	$ 12,754	$ 9,325