Share and Unit-based Plans (Tables)

12 Months Ended

Dec. 31, 2017

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, 2017, 2016 and 2015:

	2017			2016				2015
	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	—	$	—	1,612		$	62.01	9,189		$	59.25
Granted	—	—		—		—		—		—
Vested	—	—		(1,612	)	62.01		(7,577	)	58.67
Balance at end of year	—	$	—	—		$	—	1,612		$	62.01

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, 2017, 2016 and 2015:

	2017				2016				2015
	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	148,428		$	78.53	132,086		$	74.58	144,374		$	59.94
Granted	86,827		66.46		85,601		79.22		77,282		86.53
Vested	(81,205	)	75.62		(69,259	)	71.82		(86,761	)	61.29
Forfeited	(2,695	)	69.57		—		—		(2,809	)	86.72
Balance at end of year	151,355		$	73.32	148,428		$	78.53	132,086		$	74.58

Summary of Activity of SARs Awards

The following table summarizes the activity of SARs awards during the years ended December 31, 2017, 2016 and 2015:

	2017				2016				2015
	Units		Weighted Average Exercise Price		Units		Weighted Average Exercise Price		Units		Weighted Average Exercise Price
Balance at beginning of year	284,146		$	53.85	417,783		$	55.13	772,639		$	56.67
Granted	—		—		—		—		—		—
Exercised	(48,707	)	53.95		(143,822	)	53.73		(364,807	)	56.86
Special dividend adjustment	—		—		10,185		53.88		9,951		55.13
Balance at end of year	235,439		$	53.83	284,146		$	53.85	417,783		$	55.13

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, 2017, 2016 and 2015:

	2017				2016				2015
	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	322,572		$	58.18	56,315		$	73.24	46,695		$	58.89
Granted	506,906		55.33		480,371		65.00		424,442		74.71
Vested	(192,846	)	69.93		(214,114	)	77.45		(414,822	)	73.13
Forfeited	—		—		—		—		—
Balance at end of year	636,632		$	52.36	322,572		$	58.18	56,315		$	73.24

Summary of Activity of Stock Options

The following table summarizes the activity of stock options for the years ended December 31, 2017, 2016 and 2015:

	2017			2016			2015
	Options	Weighted Average Exercise Price		Options	Weighted Average Exercise Price		Options	Weighted Average Exercise Price
Balance at beginning of year	10,565	$	56.77	10,314	$	58.15	10,068	$	59.57
Granted	25,000	57.55		—	—		—	—
Exercised	—	—		—	—		—	—
Special dividend adjustment	—	—		251	56.77		246	58.15
Balance at end of year	35,565	$	57.32	10,565	$	56.77	10,314	$	58.15

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, 2017, 2016 and 2015:

	2017				2016				2015
	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	5,845		$	81.47	—		$	—	9,269		$	58.35
Granted	8,760		68.93		21,088		80.21		13,351		78.72
Vested	(10,551	)	71.69		(15,243	)	79.73		(20,162	)	72.17
Forfeited	—		—		—		—		(2,458	)	55.62
Balance at end of year	4,054		$	79.82	5,845		$	81.47	—		$	—

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, 2017, 2016 and 2015:

	2017		2016		2015
Stock awards	$	—	$	20	$	252
Stock units	6,045		6,305		6,041
LTIP units	30,161		32,957		26,622
Stock options	85		16		16
Phantom stock units	714		1,231		1,444
	$	37,005	$	40,529	$	34,375