FAIR VALUE MEASUREMENTS (Details) (USD $)	6 Months Ended					3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2010 Quoted Prices in Active Markets for Identical Assets (Level 1)	Jun. 30, 2011 Significant Unobservable Inputs (Level 3)	Jun. 30, 2010 Significant Unobservable Inputs (Level 3)	Jun. 30, 2011 Significant Unobservable Inputs (Level 3)	Jun. 30, 2010 Significant Unobservable Inputs (Level 3)	Dec. 31, 2010 Significant Unobservable Inputs (Level 3)	Jun. 30, 2011 Total	Dec. 31, 2010 Total	Jun. 10, 2011 Peak Energy Services Ltd.'s ("Peak")
FAIR VALUE MEASUREMENTS
Temporary decline in fair value of securities	$ 400,000
Unrealized pre-tax gain (loss) on auction rate securities	(100,000)	100,000
Interest rate, resetting days (in days)	28
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Auction rate securities	5,311,000		5,437,000			5,311,000		5,311,000		5,437,000	5,311,000	5,437,000
Marketable securities	128,000		3,174,000	128,000	3,174,000						128,000	3,174,000
Percentage of outstanding common shares of acquiree already owned by company (as a percent)													3.15%
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	6,503,000	5,437,000	6,503,000
Sale of auction rate securities							(1,300,000)		(1,300,000)
Unrealized (losses) gains included in other comprehensive income						(68,000)	112,000	(126,000)	112,000
Balance at the end of the period						$ 5,311,000	$ 5,315,000	$ 5,311,000	$ 5,315,000