FAIR VALUE MEASUREMENTS (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Temporary decline in fair value of securities	$ 400,000		$ 400,000
Unrealized pre-tax gain (loss) on auction rate securities			81,000
Interest rate, resetting days (in days)			28
Auction rate securities	4,326,000		4,326,000		4,245,000
Marketable securities	9,701,000		9,701,000		111,000
Long-term Debt, Fair Value	527,100,000		527,100,000		538,500,000
Total | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Auction rate securities	4,326,000		4,326,000		4,245,000
Marketable securities	9,701,000		9,701,000		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	9,701,000		9,701,000		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	4,326,000		4,326,000		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		5,379,000	4,245,000	5,437,000
Unrealized (losses) gains included in other comprehensive income	81,000	(68,000)	81,000	(126,000)
Balance at the end of the period	$ 4,326,000	$ 5,311,000	$ 4,326,000	$ 5,311,000