BORROWINGS (Details 5) (USD $)	12 Months Ended		1 Months Ended		1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 7 500% Senior notes due March 20, 2042	Mar. 20, 2012 7 500% Senior notes due March 20, 2042	Nov. 30, 2011 8 375% Senior Notes due November 15, 2041	Nov. 15, 2011 8 375% Senior Notes due November 15, 2041
Details of Company's borrowings
Aggregate principal amount of the notes			$ 115,000,000		$ 258,800,000
Interest rate (as a percent)				7.50%		8.375%
Total net proceeds from senior notes	111,418,000	250,669,000	111,400,000
Total net proceeds from senior notes					$ 250,700,000