Risk Management and Use of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of derivative instruments in statement of financial position, fair value

Hedge Product	Hedge Type	Designation		Notional Amount				Strike		Trade Date	Maturity Date	Fair value
				12/31/2012		12/31/2011						12/31/2012		12/31/2011
Swap	Interest Rate	Cash Flow	(a)	$	200,000	$	200,000	3.623	%	December 6-13, 2011	February 1, 2019	$	8,859	$	2,820
Swap	Interest Rate	Cash Flow	(a), (b)	77,000		127,000		2.703	%	December 9-13, 2011	February 1, 2016	1,343		340
Swap	Interest Rate	Cash Flow	(a)	50,000		50,000		2.470	%	December 13, 2011	February 1, 2015	458		65
Swap	Interest Rate	Cash Flow	(a)	23,000		23,000		2.513	%	December 7-12, 2011	May 1, 2015	245		27
Swap	Interest Rate	Cash Flow	(a)	27,062		27,062		2.750	%	December 21, 2011	September 30, 2017	914		244
Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.300	%	December 22, 2011	January 30, 2021	1,262		390
Swap	Interest Rate	Cash Flow	(a)	25,774		—		3.090	%	January 6, 2012	October 30, 2019	1,129		—
				$	428,610	$	452,836					$	14,210	$	3,886