DEBT (Senior Unsecured Notes) (Details) (USD $) In Thousands, unless otherwise specified			1 Months Ended	12 Months Ended		1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Senior Unsecured Notes due 2012, interest at 6.36%	Dec. 31, 2012 Senior Unsecured Notes due 2012, interest at 6.36%	Mar. 31, 2002 Senior Unsecured Notes due 2012, interest at 6.36%	Mar. 31, 2007 Series A Notes	Mar. 31, 2009 Series B Notes	Mar. 31, 2002 Minimum Senior Unsecured Notes due 2012, interest at 6.36%	Mar. 31, 2002 Maximum Senior Unsecured Notes due 2012, interest at 6.36%
Debt
Debt issuance date				Mar. 01, 2002
Debt maturity date				Mar. 01, 2012
Notes issued through a private placement					$ 150,000
Maturity period (in years)								5 years	10 years
Weighted-average interest rate (as a percent)					6.10%
Notes repaid			80,000			40,000	30,000
Fair value of long-term debt	$ 1,919	$ 84,110