Share-Based Compensation Plan (Tables)

12 Months Ended

Dec. 31, 2016

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

Summary of service condition restricted share activity

The following table provides a summary of service condition restricted share activity as of December 31, 2016:

	Shares		Weighted-Average Grant Date Fair Value
Unvested at January 1, 2014	147,881		$	24.59
Granted	44,322		$	30.11
Vested	(62,047	)	$	23.12
Forfeited	(168	)	$	27.57
Unvested at December 31, 2014	129,988		$	27.17
Granted	46,446		$	48.00
Vested	(50,827	)	$	25.70
Forfeited	(990	)	$	36.45
Unvested at December 31, 2015	124,617		$	35.46
Granted	68,535		$	23.87
Vested	(52,452	)	$	32.79
Forfeited	(4,809	)	$	30.66
Unvested at December 31, 2016	135,891		$	30.82

Performance-based Equity Awards Methodology and Assumptions

The grant date fair value of the performance awards, with market conditions, were determined using a Monte Carlo simulation method with the following assumptions:

Performance Award Grant Date		Percentage of Total Award	Grant Date Fair Value by Component ($ in millions)		Volatility	Interest Rate	Dividend Yield
February 8, 2012
	Relative Total Shareholder Return	30.00%	$0.7		33.00%	0.34%	2.20%
	Absolute Total Shareholder Return	30.00%	$0.6		33.00%	0.34%	2.20%
	EBITDA Comparison	40.00%	$0.7		33.00%	0.34%	2.20%
January 30, 2013
	Relative Total Shareholder Return	30.00%	$0.7		31.00%	0.41%	2.20%
	Absolute Total Shareholder Return	30.00%	$0.5		31.00%	0.41%	2.20%
	EBITDA Comparison	40.00%	$0.7		31.00%	0.41%	2.20%
December 13, 2013
	Relative Total Shareholder Return	50.00%	$4.7		29.00%	0.34% - 2.25%	2.40%
	Absolute Total Shareholder Return	50.00%	$2.9		29.00%	0.34% - 2.25%	2.40%
February 4, 2014
	Relative Total Shareholder Return	30.00%	$0.7		29.00%	0.62%	2.40%
	Absolute Total Shareholder Return	30.00%	$0.5		29.00%	0.62%	2.40%
	EBITDA Comparison	40.00%	$0.8		29.00%	0.62%	2.40%
February 11, 2015
	Relative Total Shareholder Return	30.00%	$0.9		22.00%	1.02%	2.50%
	Absolute Total Shareholder Return	40.00%	$0.7		22.00%	1.02%	2.50%
	EBITDA Comparison	30.00%	$0.7		22.00%	1.02%	2.50%
July 27, 2015
	Relative Total Shareholder Return	30.00%	—	(1)	22.00%	0.68%	2.50%
	Absolute Total Shareholder Return	40.00%	—	(1)	22.00%	0.68%	2.50%
	EBITDA Comparison	30.00%	—	(1)	22.00%	0.68%	2.50%
February 10, 2016
	Relative Total Shareholder Return	70.00%	$1.6		25.00%	0.71%	3.00%
	Absolute Total Shareholder Return	15.00%	$0.2		25.00%	0.71%	3.00%
	EBITDA Comparison	15.00%	$0.4		25.00%	0.71%	3.00%

⁽¹⁾Amounts round to zero.