Share and Unit-Based Plans: (Tables)

12 Months Ended

Dec. 31, 2014

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

Summary of activity of non-vested stock awards

The following table summarizes the activity of non-vested stock awards during the years ended December 31, 2014, 2013 and 2012:

	2014				2013				2012
	Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value		Shares		Weighted Average Grant Date Fair Value
Balance at beginning of year	19,001		$	56.77	20,924		$	49.36	21,130		$	40.68
Granted	—		—		8,963		61.84		9,639		54.43
Vested	(9,812	)	54.45		(10,886	)	46.70		(9,845	)	35.69
Balance at end of year	9,189		$	59.25	19,001		$	56.77	20,924		$	49.36

Summary of activity of non-vested stock units

The following table summarizes the activity of non-vested stock units during the years ended December 31, 2014, 2013 and 2012:

	2014				2013				2012
	Units		Weighted Average Grant Date Fair Value		Units		Weighted Average Grant Date Fair Value		Units		Weighted Average Grant Date Fair Value
Balance at beginning of year	137,318		$	57.24	114,677		$	52.19	576,340		$	11.71
Granted	75,309		60.50		67,920		62.01		72,322		54.43
Vested	(68,253	)	55.14		(45,279	)	51.59		(533,985	)	8.80
Balance at end of year	144,374		$	59.94	137,318		$	57.24	114,677		$	52.19

Summary of activity of SARs awards

The following table summarizes the activity of SARs awards during the years ended December 31, 2014, 2013 and 2012:

	2014				2013				2012
	Units		Weighted Average Exercise Price		Units		Weighted Average Exercise Price		Units		Weighted Average Exercise Price
Balance at beginning of year	1,070,991		$	56.66	1,164,185		$	56.66	1,156,985		$	56.55
Granted	—		—		—		—		39,932		59.57
Exercised	(298,352	)	56.63		(93,194	)	56.63		(32,732	)	56.63
Balance at end of year	772,639		$	56.67	1,070,991		$	56.66	1,164,185		$	56.66

Summary of activity of non-vested LTIP Units

The following table summarizes the activity of the non-vested LTIP Units during the years ended December 31, 2014, 2013 and 2012:

	2014				2013				2012
	Units		Weighted Average Grant Date Fair Value		Units		Weighted Average Grant Date Fair Value		Units		Weighted Average Grant Date Fair Value
Balance at beginning of year	—		$	—	200,000		$	38.63	190,000		$	43.30
Granted	725,908		51.71		332,189		66.58		315,000		40.53
Vested	(679,213	)	51.22		(518,900	)	55.81		(305,000	)	44.85
Forfeited	—		—		(13,289	)	66.58		—		—
Balance at end of year	46,695		$	58.89	—		$	—	200,000		$	38.63

Summary of activity of stock options

The following table summarizes the activity of stock options for the years ended December 31, 2014, 2013 and 2012:

	2014			2013				2012
	Options	Weighted Average Exercise Price		Options		Weighted Average Exercise Price		Options	Weighted Average Exercise Price
Balance at beginning of year	10,068	$	59.57	12,768		$	54.69	2,700	$	36.51
Granted	—	—		—		—		10,068	59.57
Exercised	—	—		(2,700	)	36.51		—	—
Balance at end of year	10,068	$	59.57	10,068		$	59.57	12,768	$	54.69

Summary of activity of non-vested phantom stock units

The following table summarizes the activity of the non-vested phantom stock units for the years ended December 31, 2014, 2013 and 2012:

	2014				2013				2012
	Stock Units		Weighted Average Grant Date Fair Value		Stock Units		Weighted Average Grant Date Fair Value		Stock Units		Weighted Average Grant Date Fair Value
Balance at beginning of year	17,575		$	58.66	—		$	—	15,745		$	34.84
Granted	10,747		65.54		34,266		59.04		7,896		57.29
Vested	(19,053	)	62.69		(16,691	)	59.44		(22,179	)	45.24
Forfeited	—		—		—		—		(1,462	)	33.74
Balance at end of year	9,269		$	58.35	17,575		$	58.66	—		$	—

Compensation cost under the share and unit-based plans

The following summarizes the compensation cost under the share and unit-based plans for the years ended December 31, 2014, 2013 and 2012:

	2014		2013		2012
Stock awards	$	365	$	497	$	598
Stock units	4,689		3,839		3,379
LTIP units	28,598		22,778		9,436
SARs	—		—		583
Stock options	16		16		21
Phantom stock units	1,205		992		953
	$	34,873	$	28,122	$	14,970