LONG-TERM DEBT (Details) (USD $)			3 Months Ended	12 Months Ended		1 Months Ended					1 Months Ended				1 Months Ended				1 Months Ended			12 Months Ended				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Derivatives designated as hedging instruments Interest-rate swap agreement	Dec. 31, 2011 Commercial paper payable through 2012 at a weighted-average interest rate of 0.4%	Dec. 31, 2010 Commercial paper payable through 2012 at a weighted-average interest rate of 0.4%	Oct. 31, 2011 Notes payable in April 2012, at an interest rate of 4.875%	Dec. 31, 2011 Notes payable in April 2012, at an interest rate of 4.875%	Dec. 31, 2010 Notes payable in April 2012, at an interest rate of 4.875%	Dec. 31, 2011 Industrial revenue bond payable in 2012 at an interest rate of 1.6%	Dec. 31, 2010 Industrial revenue bond payable in 2012 at an interest rate of 1.6%	Jul. 31, 2009 Notes payable in 2014, at an interest rate of 5.65%	Dec. 31, 2011 Notes payable in 2014, at an interest rate of 5.65%	Dec. 31, 2010 Notes payable in 2014, at an interest rate of 5.65%	Jul. 27, 2009 Notes payable in 2014, at an interest rate of 5.65%	Jul. 31, 2009 Notes payable in 2019, at an interest rate of 6.8%	Dec. 31, 2011 Notes payable in 2019, at an interest rate of 6.8%	Dec. 31, 2010 Notes payable in 2019, at an interest rate of 6.8%	Jul. 27, 2009 Notes payable in 2019, at an interest rate of 6.8%	Oct. 31, 2011 Notes payable in 2021, at an interest rate of 4.5%	Dec. 31, 2011 Notes payable in 2021, at an interest rate of 4.5%	Dec. 31, 2011 Notes payable in 2021, at an interest rate of 4.5% Interest-rate swap	Dec. 31, 2011 Debt of subsidiary companies payable through 2013 at interest rates of 7.3% to 20.6%	Dec. 31, 2010 Debt of subsidiary companies payable through 2013 at interest rates of 7.3% to 20.6%	Dec. 31, 2011 Obligations under capital leases	Dec. 31, 2010 Obligations under capital leases	Dec. 31, 2011 Revolving credit facility
Long-term debt
Weighted-average interest rate (as a percent)				0.40%	0.40%				1.70%
Interest rate on long-term debt (as a percent)			4.50%				4.875%		1.60%			5.65%		5.65%		6.80%		6.80%
Unamortized discount												$ 349,000	$ 484,000			$ 938,000	$ 1,061,000			$ 2,534,000
Fair value of interest rate swaps			3,268,000																		3,268,000
Interest rate on debt, low end of range (as a percent)																						7.30%
Interest rate on debt, high end of range (as a percent)																						20.60%
Total debt	1,568,161,000	1,286,466,000		46,500,000	158,750,000		300,000,000	300,000,000	8,000,000	8,000,000		399,651,000	399,516,000			399,062,000	398,939,000			400,734,000		13,585,000	20,469,000	629,000	792,000
Less current portion	13,411,000	2,941,000
Total long-term debt	1,554,750,000	1,283,525,000
Long-term debt, maximum amount outstanding				574,500,000
Long-term debt, average amount outstanding				289,800,000
Revolving credit facility, maximum borrowing capacity																										800,000,000
Revolving credit facility, combined multicurrency borrowing limit																										100,000,000
Issuance of debt						300,000,000					400,000,000				400,000,000				400,000,000
Number of swap agreements			4
Notional amounts of derivatives			400,000,000
Reference rate for variable rate			six-month London Interbank Offered Rate (LIBOR)
Net settlement benefit due to reset of variable rates semi-annually at each net settlement date			1,600,000
Long-term debt maturing in years
2012	321,400,000
2013	47,100,000
2014	399,800,000
2015	0
2016	$ 0