SHAREHOLDERS' EQUITY AND SHARE-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of assumptions used to determine the fair value of options as of the grant date

The following assumptions were used to determine the fair values as of the grant date:

2017

2016

2015

Black-Scholes

Binomial

Black-Scholes

Binomial

Black-Scholes

Binomial

Risk-free interest rate (%)

1.89 – 2.29

0.77 – 2.38

1.25 – 1.89

0.23 – 2.23

1.50 – 1.91

0.02 – 2.34

Expected stock price volatility (%)

61.49 – 71.52

66.68 – 71.52

59.75 – 62.14

59.76 – 62.14

55.06 – 59.73

Expected dividend yield

—

Expected option life (in years)

6.00 – 7.50

2.55 – 4.82

6.00 – 6.25

4.06 – 4.88

6.00 – 6.25

4.08 – 4.92

Fair value

$13.57 – $24.80

$11.94 – $24.30

$11.15 – $18.60

$11.06 – $19.27

$10.01 – $17.66

$9.91 – $18.05

Summary of the weighted average fair value of stock options granted, the total intrinsic value of stock options exercised and the fair value of options vested

The following table summarizes the weighted average grant date fair value of stock options granted per share, the total intrinsic value of stock options exercised and the grant date fair value of stock options that vested during the years ended December 31:



(in thousands, except per share amounts)	2017		2016		2015

Weighted average grant date fair value of stock options granted per share	$	20.44	$	16.82	$	13.20
Intrinsic value of stock options exercised	3,028		18,209		1,998
Grant date fair value of stock options that vested	2,279		2,698		1,616

Summary of the activity of the entity's stock options

The following table summarizes the activity related to our stock options:



	Number of options		Weighted average exercise price		Weighted average contractual term (in years)	Aggregate intrinsic value (in thousands)

Outstanding at December 31, 2016	1,996,509		$	25.98	5.32	$	15,942
Granted	243,930		33.28
Exercised	(223,060	)	10.64
Forfeited	(271,473	)	30.12

Outstanding at December 31, 2017	1,745,906		28.20		4.96	10,202

Exercisable at December 31, 2017	1,140,333		23.10		3.30	9,160

Shares authorized under stock option plans, by exercise price range

The following table summarizes information about stock options outstanding and exercisable at December 31, 2017:



	Options outstanding				Options exercisable
Exercise price range ⁽¹⁾	Number	Weighted average remaining contractual life (in years)	Weighted average exercise price		Number	Weighted average remaining contractual life (in years)	Weighted average exercise price

Up to $10.00	286,252	0.53	$	9.14	286,252	0.53	$	9.14
$10.01 — $20.00	246,479	7.27	18.79		163,424	7.25	18.79
$20.01 — $30.00	813,730	4.86	25.11		559,576	3.21	24.11
$30.01 — $40.00	224,695	8.03	36.27		53,924	4.78	32.67
$60.01 — $70.00	71,000	4.19	60.73		51,375	4.19	60.74
$70.01 — $80.00	25,000	6.86	72.78		4,688	6.86	72.78
$80.01 — $90.00	30,000	6.35	86.22		8,438	5.94	85.43
$90.01 — $100.00	46,875	6.15	95.64		11,250	5.95	95.38
$100.01 — $110.00	1,875	6.37	105.11		1,406	6.37	105.11

	1,745,906				1,140,333

______________________________________


⁽¹⁾	These options contain market-based components as described above.

Shares authorized under stock option plans by vesting price range

The following table summarizes the market prices necessary in order for the market-based options to begin to vest:



	Market-based options
Vesting price	Ordinary performance		Extraordinary performance

$40.01 — $50.00	9,525		—
$50.01 — $60.00	82,600		11,653
$60.01 — $70.00	14,148		6,325
$70.01 — $80.00	1,250		10,333
$80.01 — $90.00	—		30,963
$90.01 — $100.00	—		7,075
$110.01 — $120.00	—		625
$140.01 — $150.00	12,500		—
$170.01 — $180.00	12,500		—
$180.01 — $190.00	7,500		19,625
Over $190.00	15,000		25,000

Total	155,023		111,599

Weighted average share price	$	45.99	$	45.83

Restricted stock and restricted stock units activity

The following table summarizes the activity related to our restricted shares:



	Number of restricted shares

Outstanding at December 31, 2016	231,730
Granted	245,655
Issued	(55,385	)
Forfeited/canceled	(65,491	)

Outstanding at December 31, 2017	356,509