FINANCIAL INSTRUMENTS (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Dec. 21, 2012
Assets:
Marketable securities	$ 5,814,000	$ 20,604,000
Liabilities:
Current maturities of long-term debt	0	(15,844,000)	(15,844,000)
Long-term debt, net of current maturities	(580,000,000)	(580,000,000)	(580,000,000)
Long-term marketable equity securities
Gross unrealized losses	0	0
Carrying values of investments accounted for under cost method	114,300,000	113,800,000
Long-term marketable equity securities
Long-term marketable equity securities
Cost basis	42,100,000	42,100,000
Gross unrealized losses	14,900,000	10,800,000
Carrying Value
Assets:
Cash and cash equivalents	673,757,000	749,977,000
Marketable securities	5,814,000	20,604,000
Liabilities:
Current maturities of long-term debt	0	(15,844,000)
Fair value of contingent consideration arrangement	42,295,000
Long-term debt, net of current maturities	(580,000,000)	(580,000,000)
Carrying Value | Long-term marketable equity securities
Assets:
Long-term investments	27,152,000	31,244,000
Fair Value
Assets:
Cash and cash equivalents	673,757,000	749,977,000
Marketable securities	5,814,000	20,604,000
Liabilities:
Current maturities of long-term debt	0	(15,875,000)
Fair value of contingent consideration arrangement	42,295,000
Long-term debt, net of current maturities	(572,784,000)	(581,994,000)
Fair Value | Long-term marketable equity securities
Assets:
Long-term investments	$ 27,152,000	$ 31,244,000