Stock-Based Compensation (Tables)

As of June 30, 2015, the unrecognized compensation cost and remaining weighted-average amortization related to stock-based awards were as follows:

							Performance-
							based
					Restricted		Restricted
		Stock	Restricted		Stock		Stock
(in thousands)		Options	Shares		Units		Units⁽¹⁾
Unrecognized compensation cost	$	5,390	$	395	$	8,821	$	2,972
Remaining weighted-average
amortization period	2.0 years		0.6 years		2.6 years		2.0 years

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

The weighted-average assumptions used to value the options granted during the three and six months ended June 30, 2015 and 2014, were as follows:

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, 2014	2,437	$	20.07
Granted	289	$	23.14
Exercised	(80)	$	18.30
Forfeited or expired	(15)	$	22.83
Outstanding as of June 30, 2015	2,631	$	20.45	5.13	$	6,614
Exercisable as of June 30, 2015	1,847	$	20.13	3.31	$	5,461

The following table summarizes activities related to the Company’s restricted shares:

			Weighted-
			Average
	Number of		Grant Date
(in thousands, except per share data)	Shares		Fair Value
Non-vested shares outstanding as of December 31, 2014	109	$	16.33
Vested	(70)	$	16.84
Forfeited	(1)	$	16.93
Non-vested shares outstanding as of June 30, 2015	38	$	15.39

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, 2014	412	$	20.33
Granted	205	$	23.28
Vested	(142)	$	20.05
Forfeited	(6)	$	20.61
Non-vested awards outstanding as of June 30, 2015	469	$	21.70

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, 2014	274	$	18.56
Granted⁽¹⁾	76	$	23.14
Forfeited or expired	(53)	$	18.57
Non-vested units outstanding as of June 30, 2015	297	$	19.74

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