EARNINGS PER COMMON SHARE (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Series A Units	Mar. 31, 2014 Series B Units	Mar. 31, 2014 Series C Units	Mar. 31, 2014 Operating Partnership 2.375% Exchangeable Senior Notes	Jun. 21, 2013 Operating Partnership 2.375% Exchangeable Senior Notes
Earnings Per Common Share
Principal amount of notes						$ 250,000	$ 250,000
Interest rate (as a percent)						2.375%	2.375%
Exchange price (in dollars per share)						$ 55.69
Shares related to the Notes included in the computation for diluted earnings per share	0
Exchangeable preferred operating partnership units settled in cash, minimum			115,000
Units outstanding (in dollars)				$ 33,568	$ 17,177
Average closing price of common stock (in dollars per share)	$ 46.35
Number of shares which would have been issued upon assuming full exchange	989,980	989,980		724,232	370,585