Equity-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2017

The following table details our compensation expense and the related income tax benefit as of December 31:

(Dollars in thousands)	2017		2016		2015
Employee equity-based compensation expense:
Performance stock awards	$	3,582	$	3,437	$	3,877
Restricted stock units		1,140		953		881
Total employee equity-based compensation expense	$	4,722	$	4,390	$	4,758

Deferred compensation stock equivalent units expense	$	657	$	732	$	376

Total tax benefit recognized for shared-based payment awards	$	379	$	317	$	319

The following table presents the key inputs used in calculating the fair value of the PSAs in 2017, 2016 and 2015, and the resulting fair values:

	2017			2016			2015
Stock price as of valuation date	$	43.60		$	25.92		$	40.00
Risk-free rate		1.61	%		0.88	%		1.07	%
Expected volatility		24.22	%		23.82	%		21.09	%
Expected dividends		3.44	%		5.79	%		3.75	%
Expected term (years)		3.00			3.00			3.00
Fair value of a performance share	$	53.85		$	30.02		$	36.71

The following table summarizes outstanding PSAs as of December 31, 2017, 2016 and 2015, and the changes during those years:

	2017					2016					2015
(Dollars in thousands, except per share amounts)	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Unvested shares outstanding at January 1		203,788		$	32.59		161,049		$	41.26		160,233		$	53.86
Granted		78,033		$	53.85		125,469		$	30.02		78,974		$	36.71
Vested		(78,129	)	$	36.71		(82,730	)	$	45.57		(77,078	)	$	62.78
Forfeited		(3,061	)	$	34.68		—		$	—		(1,080	)	$	41.29
Unvested shares outstanding at December 31		200,631		$	39.19		203,788		$	32.59		161,049		$	41.26
Total grant date fair value of share awards vested during the year	$	2,868				$	3,770				$	4,839
Aggregate intrinsic value of unvested share awards at December 31	$	10,011				$	8,488				$	4,697

The following table summarizes outstanding RSU awards as of December 31, 2017, 2016 and 2015, and the changes during those years:

	2017					2016					2015
(Dollars in thousands, except per share amounts)	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Unvested shares outstanding at January 1		71,420		$	31.61		44,531		$	40.95		32,455		$	42.24
Granted		26,507		$	43.64		43,320		$	26.08		27,820		$	39.99
Vested		(29,039	)	$	39.65		(16,431	)	$	39.92		(15,385	)	$	44.50
Forfeited		(1,017	)	$	31.63		—		$	—		(359	)	$	40.27
Unvested shares outstanding at December 31		67,871		$	32.87		71,420		$	31.61		44,531		$	40.95
Total grant date fair value of RSU awards vested during the year	$	1,151				$	656				$	289
Aggregate intrinsic value of unvested RSU awards at December 31	$	3,387				$	2,975				$	1,347