Stock Compensation Plans

Pursuant to the Company’s 2016 Stock Incentive Plan, as amended, the Company may issue stock options, restricted stock awards (“RSAs”), restricted stock units (“RSUs”), stock appreciation rights, stock purchase warrants, phantom stock and dividend equivalents to certain employees and non-employee directors of the Company and its subsidiaries. There were no outstanding stock options or unvested RSAs as of March 31, 2018 and 2017.

RSUs are granted under the Company’s long-term incentive plan at no cost to the recipient. RSUs vest ratably over three years or cliff vest after three or five years of continued employment from the date of the grant. RSUs entitle the recipient to receive cash dividends equivalent to any dividends paid on the underlying common stock during the period the RSUs are outstanding. RSU dividends are accrued during the vesting period and are paid at the time of vesting. While a portion of RSUs are time-vesting awards, others vest subject to the attainment of specified performance goals referred to as “Performance-based RSUs.” All RSUs are subject to forfeiture until vested.

Performance-based RSUs are granted at the target amount of awards. Based on the Company’s attainment of specified performance goals and consideration of market conditions, the number of shares that vest can be adjusted to a minimum of zero and to a maximum of 200% of the target. The amount of performance-based RSUs that are eligible to vest is determined at the end of each performance period and is then added together to determine the total number of performance shares that are eligible to vest. Performance-based RSUs cliff vest three years from the date of grant.

Compensation costs for the time-based awards are based on the quoted market price of the Company’s stock at the grant date. Compensation costs associated with performance-based RSUs are based on grant date fair value which considers both market and performance conditions, and is subject to subsequent adjustments based on the changes in the Company’s stock price and the projected outcome of the performance criteria. Compensation costs of both time-based and performance-based awards are recognized on a straight-line basis from the grant date until the vesting date of each grant.

The following table presents a summary of the total share-based compensation expense and the related net tax benefit associated with the Company’s various employee share-based compensation plans for the three months ended March 31, 2018 and 2017:




($ in thousands)	Three Months Ended March 31,
($ in thousands)	2018		2017
Stock compensation costs	$	6,158	$	5,151
Related net tax benefits for stock compensation plans	$	4,778	$	4,414

The following table presents a summary of the activity for the Company’s time-based and performance-based RSUs for the three months ended March 31, 2018 based on the target amount of awards:




	Three Months Ended March 31, 2018
	Time-Based RSUs				Performance-Based RSUs
	Shares		Weighted-Average Grant Date Fair Value		Shares		Weighted-Average Grant Date Fair Value
Outstanding, at beginning of period	1,166,580		$	42.00	424,299		$	41.44
Granted	389,667		67.32		120,286		70.13
Vested	(312,413	)	39.97		(133,295	)	41.15
Forfeited	(29,223	)	44.62		—		—
Outstanding, at end of period	1,214,611		$	50.58	411,290		$	49.93

As of March 31, 2018, total unrecognized compensation costs related to time-based and performance-based RSUs amounted to $46.8 million and $26.0 million, respectively. These costs are expected to be recognized over a weighted-average period of 2.44 years and 2.37 years for time-based and performance-based RSUs, respectively.