SUBSEQUENT EVENTS (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Apr. 25, 2012
Common stock issuance - Continous common equity program [Member]
Subsequent Event [Line Items]
Subsequent event date	April 25, 2012
Common shares issued and sold (in shares)	143,213
Average price (in dollars per share)	$ 50.62
Proceeds from issuance of common stock		$ 7,200,000.0
Common stock remaining to sell under the program (in shares)		901,652
Repayment of mortgage loan [Member]
Subsequent Event [Line Items]
Loan balance repayment	$ 8,700,000.0
Interest rate	7.98%
Maturity date	Jun. 01, 2012
Subsequent event date	April 2, 2012