Equity-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Share Based Compensation [Abstract]

Details of Equity-Based Compensation Expense and Related Income Tax Benefit

The following table details equity-based compensation expense and the related income tax benefit:

	Three Months Ended March 31,
(Dollars in thousands)	2018		2017
Employee equity-based compensation expense:
Performance shares	$	936	$	868
Restricted stock units		480		289
Accelerated share-based termination benefits in connection with the merger		1,678		—
Total employee equity-based compensation expense	$	3,094	$	1,157
Deferred compensation stock equivalent units expense	$	185	$	161
Total tax benefit recognized for share-based expense	$	111	$	93

Fair Value of Performance Share Awards

The following table presents the key inputs used in the Monte Carlo simulation to calculate the fair value of the performance share awards in 2018 and 2017:

	Three Months Ended March 31,
	2018			2017
Stock price as of valuation date	$	54.00		$	43.60
Risk-free rate		2.46	%		1.61	%
Expected volatility		23.74	%		24.22	%
Expected dividends		2.96	%		3.44	%
Expected term (years)		3.00			3.00
Fair value	$	75.37		$	53.85

Summary of Outstanding Performance Share Awards

The following table summarizes outstanding performance share awards as of March 31, 2018 and changes during the three months ended March 31, 2018:

(Dollars in thousands, except grant date fair value)	Shares		Weighted-Avg. Grant Date Fair Value		Aggregate Intrinsic Value
Unvested shares outstanding at January 1, 2018		200,631	$	39.19
Granted		67,747	$	75.37
Unvested shares outstanding at March 31, 2018		268,378	$	48.32	$	13,969

Summary of Outstanding RSU Awards

The following table summarizes outstanding RSU awards as of March 31, 2018 and changes during the three months ended March 31, 2018:

(Dollars in thousands, except grant date fair value)	Shares			Weighted-Avg. Grant Date Fair Value		Aggregate Intrinsic Value
Unvested shares outstanding at January 1, 2018		67,871		$	32.87
Granted		25,584		$	53.74
Vested		(500	)	$	40.13
Unvested shares outstanding at March 31, 2018		92,955		$	38.58	$	4,838