SHAREHOLDERS' EQUITY AND SHARE-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2018

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:

2018

2017

2016

Black-Scholes

Binomial

Black-Scholes

Binomial

Black-Scholes

Binomial

Risk-free interest rate (%)

2.66 – 3.10

1.64 – 3.22

1.89 – 2.29

0.77 – 2.38

1.25 – 1.89

0.23 – 2.23

Expected stock price volatility (%)

70.31 – 71.86

71.36 – 71.86

61.49 – 71.52

66.68 – 71.52

59.75 – 62.14

59.76 – 62.14

Expected dividend yield

—

Expected option life (in years)

6.00 – 6.25

2.56 – 4.33

6.00 – 7.50

2.55 – 4.82

6.00 – 6.25

4.06 – 4.88

Fair value

$16.17 – $19.68

$14.67 – $20.26

$13.57 – $24.80

$11.94 – $24.30

$11.15 – $18.60

$11.06 – $19.27

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)	2018		2017		2016

Weighted average grant date fair value of stock options granted per share	$	16.31	$	20.44	$	16.82
Intrinsic value of stock options exercised	4,609		3,028		18,209
Grant date fair value of stock options that vested	1,760		2,279		2,698

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, 2017	1,745,906		$	28.20	4.96	$	10,202
Granted	276,876		25.15
Exercised	(330,537	)	11.33
Forfeited	(251,679	)	32.21

Outstanding at December 31, 2018	1,440,566		30.78		5.04	945

Exercisable at December 31, 2018	874,304		27.42		3.20	902

Shares authorized under stock option plans, by exercise price range

The following table summarizes information about stock options outstanding and exercisable at December 31, 2018:



	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

$10.01 — $20.00	212,667	6.06	$	18.79	203,344	6.05	$	18.79
$20.01 — $30.00	925,563	4.79	24.60		537,607	2.07	23.81
$30.01 — $40.00	132,586	6.20	34.63		54,478	3.54	32.82
$60.01 — $70.00	71,000	3.19	60.73		51,375	3.19	60.74
$70.01 — $80.00	25,000	4.51	72.78		6,250	0.45	72.78
$80.01 — $90.00	25,000	5.60	86.69		6,250	5.60	86.69
$90.01 — $100.00	46,875	5.00	95.64		13,125	4.51	95.59
$100.01 — $110.00	1,875	0.45	105.11		1,875	0.45	105.11

	1,440,566				874,304

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⁽¹⁾	These options contain market-based and performance-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	6,400		—
$50.01 — $60.00	60,164		9,323
$60.01 — $70.00	16,648		6,325
$70.01 — $80.00	—		11,500
$80.01 — $90.00	—		19,080
$90.01 — $100.00	—		8,325
$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		23,750

Total	130,712		97,928

Weighted average share price	$	49.46	$	47.79

Restricted shares and restricted share units activity

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



	Number of restricted shares and restricted share units

Outstanding at December 31, 2017	356,509
Granted	375,524
Issued	(111,565	)
Forfeited/canceled	(134,662	)

Outstanding at December 31, 2018	485,806