Share and Unit-Based Plans: (Tables)

6 Months Ended

Jun. 30, 2012

Share and Unit-Based Plans:

Compensation cost under the share and unit-based plans

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	2012		2011		2012		2011
LTIP Units	$	2,321	$	2,575	$	3,868	$	4,477
Stock awards		124		84		220		578
Stock units		383		2,930		2,603		5,742
SARs		82		302		82		623
Phantom stock units		255		242		509		482
	$	3,165	$	6,133	$	7,282	$	11,902

Summary of activity of non-vested LTIP Units, stock awards, phantom stock and stock units

	LTIP Units					Stock Awards					Phantom Stock					Stock Units
	Units			Value(1)		Shares			Value(1)		Units			Value(1)		Units			Value(1)
Balance January 1, 2012		190,000		$	43.30		21,130		$	40.68		15,745		$	34.84		576,340		$	11.71
Granted(2)		295,000			40.13		9,639			54.43		4,200			56.09		72,322			54.43
Vested(2)		(285,000	)		43.30		(9,845	)		35.69		(12,065	)		42.23		(533,985	)		15.24
Forfeited		—			—		—			—		—			—		—			—
Balance at June 30, 2012		200,000		$	38.63		20,924		$	49.36		7,880		$	34.84		114,677		$	52.19

(1)

Value represents the weighted-average grant date fair value.

(2)

On February 7, 2012, the compensation committee determined that the LTIP Units granted under the LTIP on February 28, 2011 had vested at the 150% level based on the Company's percentile ranking in terms of Total Return per common stock share to the Total Return of a group of peer REITs during the period of February 1, 2011 to January 31, 2012. As a result, the compensation committee granted an additional 95,000 LTIP Units, which vested as of January 31, 2012.

Summary of activity of SARs and stock options outstanding

	SARs					Stock Options
	Shares			Value(1)		Shares		Value(1)
Balance January 1, 2012		1,156,985		$	56.55		13,500	$	30.08
Granted		—			—		—		—
Exercised		(32,732	)		56.63		—		—
Forfeited		—			—		—		—
Balance at June 30, 2012		1,124,253		$	56.55		13,500	$	30.08

(1)

Value represents the weighted-average exercise price.