Share and Unit-Based Plans: (Tables)

3 Months Ended

Mar. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Compensation cost under the share and unit-based plans

The following summarizes the compensation cost under the share and unit-based plans:

	For the Three Months Ended March 31,
	2014		2013
LTIP Units	$	18,240	$	2,957
Stock awards	114		110
Stock units	1,682		1,824
Stock options	4		4
Phantom stock units	306		242
	$	20,346	$	5,137

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

The following table summarizes the activity of the non-vested LTIP Units, stock awards, phantom stock units and stock units:

	LTIP Units				Stock Awards				Phantom Stock Units				Stock Units
	Units		Value(1)		Shares		Value(1)		Units		Value(1)		Units		Value(1)
Balance at January 1, 2014	—		$	—	19,001		$	56.77	17,575		$	58.66	137,318		$	57.24
Granted	589,443		53.18		—		—		5,409		59.61		70,271		60.22
Vested	(246,471	)	60.25		(9,812	)	54.45		(4,978	)	59.37		(67,917	)	55.06
Forfeited	—		—		—		—		—		—		—		—
Balance at March 31, 2014	342,972		$	48.11	9,189		$	59.25	18,006		$	58.75	139,672		$	59.80

(1) Value represents the weighted average grant date fair value.

Summary of activity of SARs and stock options outstanding

The following table summarizes the activity of the stock appreciations rights ("SARs") and stock options outstanding:

	SARs			Stock Options
	Shares	Value(1)		Shares	Value(1)
Balance at January 1, 2014	1,070,991	$	56.66	10,068	$	59.57
Granted	—	—		—	—
Exercised	—	—		—	—
Forfeited	—	—		—	—
Balance at March 31, 2014	1,070,991	$	56.66	10,068	$	59.57

(1) Value represents the weighted average exercise price.