EQUITY ATM Equity Program (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 At The Market Equity Program	Sep. 30, 2014 At The Market Equity Program	Sep. 30, 2014 Commissions At The Market Equity Program	Sep. 30, 2014 Commissions At The Market Equity Program	Sep. 30, 2014 Other Offering Costs At The Market Equity Program	Sep. 30, 2014 Other Offering Costs At The Market Equity Program
Equity [Line Items]
Number of shares of common stock issued through ATM program			599,582	2,710,067
Weighted average price per share			$ 35.01	$ 33.84
Proceeds, gross			$ 20,994	$ 91,707
Payments of stock issuance costs					(210)	(918)	(49)	(145)
Proceeds, net	$ 104,148	$ 24,790	$ 20,735	$ 90,644