Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Restricted Stock Units (RSU) and Performance Share Awards (PSAs) [Member]

Summary of Share Based Compensation Activity

The following table summarizes RSU and PSA activity during the past three years:

Units	2017			2016			2015
Balance at January 1,		679,038			674,523			888,942
Granted		375,435			302,722			164,666
Forfeited		(96,306	)		(148,232	)		(92,183	)
Shares delivered		(28,781	)		(149,975	)		(286,902	)
Balance at December 31,		929,386			679,038			674,523

Compensation Expense for Stock Option Activity

	2017		2016		2015
Compensation expense	$	4,843	$	3,154	$	1,758

Stock Only Stock Appreciation Rights (SOSARs) [Member]

Summary of Share Based Compensation Activity

The following table sets forth information related to outstanding SOSARS:

	2017					2016					2015
SOSARS	Shares			Wtd Avg Exercise Price		Shares			Wtd Avg Exercise Price		Shares			Wtd Avg Exercise Price
Outstanding at January 1,		2,736,616		$	17.64		2,199,742		$	17.82		1,864,707		$	16.20
Granted		—			—		743,925			17.54		423,590		24.62
Exercised		(157,140	)		13.76		(61,190	)		10.70		(70,347	)		14.12
Canceled / forfeited		(17,630	)		18.46		(145,861	)		22.80		(18,208	)		25.41
Outstanding at December 31,		2,561,846		$	17.87		2,736,616		$	17.64		2,199,742		$	17.82
Exercisable at December 31,		2,011,075			17.56		1,740,591		16.19			1,504,599			14.48
Vested and expected to vest		2,561,846					2,725,611					2,178,708
SOSAR Grants
Weighted average grant date    fair value per share		—				$	4.07				$	7.46
Aggregate grant date    fair value (in thousands)		—				$	3,013				$	3,134
Black-Scholes assumptions
Dividend yield		—					2.85	%				1.94	%
Risk free rate of return		—					1.34	%				1.64	%
Volatility		—					31.97	%				36.38	%
Expected life		—				6					6
Compensation expense    (in thousands)	$	1,371				$	2,735				$	2,645