FAIR VALUE MEASUREMENTS (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Temporary decline in fair value of securities	$ 500,000
Unrealized pre-tax gain (loss) on auction rate securities	0
Interest rate, resetting days (in days)	28
Auction rate securities	4,245,000		4,245,000
Marketable securities	4,997,000		111,000
Long-term Debt, Fair Value	541,000,000		538,500,000
Total | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Auction rate securities	4,245,000		4,245,000
Marketable securities	4,997,000		111,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Auction rate securities
Marketable securities	4,997,000		111,000
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Auction rate securities
Marketable securities
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Auction rate securities	4,245,000		4,245,000
Marketable securities
Changes in the entity's auction rate securities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance at the beginning of the period	4,245,000	5,437,000
Unrealized (losses) gains included in other comprehensive income	0	(58,000)
Balance at the end of the period	$ 4,245,000	$ 5,379,000