Stock-Based Compensation (Tables)

As of March 31, 2017, 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)		Options	Units		Units⁽¹⁾
Unrecognized compensation cost		$ 1,505		$ 14,431		$ 6,090
Remaining weighted-average
amortization period	1.4 years			2.8 years		2.2 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	(256)	20.07
Forfeited or expired	(10)	19.78
Outstanding as of March 31, 2017	931	$19.35	5.49	$ 11,585
Exercisable as of March 31, 2017	771	$18.58	3.74	$ 10,195

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	226	31.40
Vested	(165)	21.04
Forfeited	(8)	25.52
Non-vested awards outstanding as of March 31, 2017	578	$26.42

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	(36)	17.58
Non-vested units outstanding as of March 31, 2017	335	$26.15

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