Stock-Based Compensation (Tables)

As of March 31, 2018, the unrecognized compensation cost and remaining weighted-average amortization period related to stock-based awards were as follows:

					Performance-
					based
			Restricted		Restricted
		Stock	Stock		Stock
(in thousands, except remaining period data)		Options	Units		Units⁽¹⁾
Unrecognized compensation cost		$ 266		$ 18,401		$ 5,985
Remaining weighted-average
amortization period	0.9 years			3.1 years		2.1 years

⁽¹⁾ Based on the probable achievement of the performance goals identified in each award.

The following table summarizes activities relating to the Company’s stock options:

			Weighted-
		Weighted-	Average	Aggregate
	Number of	Average	Remaining	Intrinsic
	Options	Exercise	Contractual	Value
	(in thousands)	Price	Term (Years)	(in thousands)
Outstanding as of December 31, 2017	596	$19.72
Exercised	(168)	18.40
Forfeited or expired	(19)	22.97
Outstanding as of March 31, 2018	409	$20.12	4.99	$ 3,985
Exercisable as of March 31, 2018	372	$19.82	3.95	$ 3,735

The following table summarizes the activities related to the Company’s time-based restricted stock units:

		Weighted-
	Number of	Average
	Units	Grant Date
	(in thousands)	Fair Value
Non-vested awards outstanding as of December 31, 2017	593	$27.47
Granted	333	30.01
Vested	(198)	26.21
Forfeited	(56)	26.60
Non-vested awards outstanding as of March 31, 2018	672	$29.18

The following table summarizes the activities related to the Company’s performance-based restricted stock units:

		Weighted-
	Number of	Average
	Units	Grant Date
	(in thousands)	Fair Value
Non-vested units outstanding as of December 31, 2017	346	$26.88
Granted ⁽¹⁾	109	29.92
Forfeited or expired	(145)	23.97
Non-vested units outstanding as of March 31, 2018	310	$29.31

⁽¹⁾Represents target number of units that can vest based on the achievement of the performance goals.