CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY [Abstract]
Issuance of common stock (in shares)	71,925	163,313	277,761
Purchase of common stock (in shares)		261,577	30,691
Dividends paid on common stock (in dollars per shares)	$ 0.90	$ 0.85	$ 0.75