DERIVATIVE AND HEDGING ACTIVITIES (Details) (USD $) In Thousands, unless otherwise specified		12 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended		0 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 Cash flow hedges	Dec. 31, 2011 Unsecured Term Loan	Dec. 31, 2012 Unsecured Term Loan	Dec. 31, 2012 Unsecured Term Loan Minimum	Dec. 31, 2012 Unsecured Term Loan Maximum	Dec. 31, 2012 Interest rate swaps	Dec. 31, 2012 Interest rate swaps Derivatives designated as hedging instruments	Jul. 19, 2012 Interest rate swaps Unsecured Term Loan	Jul. 19, 2012 Interest rate swaps Unsecured Term Loan Minimum	Jul. 19, 2012 Interest rate swaps Unsecured Term Loan Maximum	Dec. 31, 2012 0.6800% Interest rate swap Cash flow hedges	Dec. 31, 2012 0.6925% Interest rate swap Cash flow hedges
Derivative and hedging activities
Unsecured term Loan			$ 250,000						$ 250,000
Unsecured term Loan, maturity term			5 years						5 years
Variable rate basis				LIBOR					one-month LIBOR
Interest rate spread (as a percent)				1.30%	1.00%	2.00%				1.00%	2.00%
Interest rate (as a percent)									0.685%
Minimum aggregate principal amount of indebtedness in default upon which counterparties could declare the Company in default on its derivative obligations	20,000
Fair value of derivative financial instruments								1,296
Estimated amount reclassified from accumulated other comprehensive income to interest expense over the next twelve months							1,100
Notional Amount												150,000	100,000
Fixed Interest Rate (as a percent)												0.68%	0.6925%
Variable Interest Rate												one-month LIBOR	one-month LIBOR
Amount of gain (loss) recognized in accumulated other comprehensive income on interest rate derivatives (effective portion)		(1,722)
Amount of gain (loss) reclassified from accumulated other comprehensive income into income as interest expense (effective portion)		(426)
Fair value of derivatives in net liability position							1,296
Termination value							$ 1,345