Stock-Based Compensation (Tables)

As of September 30, 2017, the unrecognized compensation cost and remaining weighted-average amortization related to stock-based awards were as follows:

					Performance-
					based
			Restricted		Restricted
		Stock	Stock		Stock
(in thousands)		Options	Units		Units⁽¹⁾
Unrecognized compensation cost		$ 938		$ 13,111		$ 5,328
Remaining weighted-average
amortization period	0.9 years			2.4 years		1.8 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
		Average	Remaining	Aggregate
	Number of	Exercise	Contractual	Intrinsic
(in thousands, except per share data)	Options	Price	Term (Years)	Value
Outstanding as of December 31, 2016	1,197	$19.51
Exercised	(502)	19.56
Forfeited or expired	(14)	20.51
Outstanding as of September 30, 2017	681	$19.45	5.31	$ 10,015
Exercisable as of September 30, 2017	527	$18.39	3.54	$ 8,304

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

		Weighted-
		Average
	Number of	Grant Date
(in thousands, except per share data)	Units	Fair Value
Non-vested awards outstanding as of December 31, 2016	525	$22.57
Granted	302	31.64
Vested	(185)	21.43
Forfeited	(34)	23.96
Non-vested awards outstanding as of September 30, 2017	608	$27.34

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

		Weighted-
		Average
	Number of	Grant Date
(in thousands, except per share data)	Units	Fair Value
Non-vested units outstanding as of December 31, 2016	227	$21.43
Granted ⁽¹⁾	172	31.60
Forfeited or expired	(51)	18.69
Non-vested units outstanding as of September 30, 2017	348	$26.84

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