Stock-Based Compensation (Tables)

As of June 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		$ 1,223		$ 13,673		$ 5,195
Remaining weighted-average
amortization period	1.1 years			2.6 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	(411)	19.71
Forfeited or expired	(11)	19.99
Outstanding as of June 30, 2017	775	$19.40	5.35	$ 10,004
Exercisable as of June 30, 2017	619	$18.46	3.64	$ 8,559

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	264	31.50
Vested	(177)	21.01
Forfeited	(29)	23.39
Non-vested awards outstanding as of June 30, 2017	583	$27.05

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⁾	144	31.40
Forfeited or expired	(50)	18.69
Non-vested units outstanding as of June 30, 2017	321	$26.35

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