15.	Share Plans

The Company adopted an equity incentive plan (Plan) on

February 10, 2010

in connection with its initial public offering. The Plan, as amended, allows for granting of up to

9.1

million share-based awards to executives, directors and employees. Awards available for grant under the Plan include stock options, stock appreciation rights, restricted stock, other share-based awards and performance-based compensation awards. Total share-based compensation expense related to the Plan, net of estimated forfeitures, was

$14,563,

$10,205

and

$9,493

for the years ended

December 31, 2018,

2017

and

2016,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.

Stock Options

- Stock options granted in

2018

have an exercise price between

$43.88

per share and

$45.29

per share; stock options granted in

2017

have an exercise price between

$40.12

per share and

$48.98

per share; and stock options granted in

2016

have an exercise price between

$33.23

per share and

$35.37

per share. Stock options vest in equal installments over

four

years, subject to the grantee’s continued employment or service and expire

ten

years after the date of grant.

Stock option exercises can be net-share settled such that the Company withholds shares with value equivalent to the exercise price of the stock option awards plus the employees’ minimum statutory obligation for the applicable income and other employment taxes. Total shares withheld were

63,817,

9,033

and

473,743

2018,

2017

and

2016,

respectively, and were based on the value of the stock on the exercise dates. The net-share settlement has the effect of share repurchases by the Company as they reduce the number of shares that would have otherwise been issued.

Employees can also utilize a cashless for cash exercise of stock options, such that all exercised shares will be sold in the market immediately. Cash equivalent to the exercise price of the awards plus the employees’ minimum statutory tax obligations is remitted to the Company, with the remaining cash being transferred to the employee. Total net proceeds from the cashless for cash exercise of stock options were

$5,614,

$6,951

and

$1,623

2018,

2017

and

2016,

respectively, and are reflected as a financing activity in the consolidated statement of cash flows.

Total payments made by the Company for the employees’ tax obligations to the taxing authorities were

$3,846,

$4,301

and

$13,056

2018,

2017

and

2016,

respectively, and are reflected as a financing activity in the consolidated statements of cash flows.

The grant-date fair value of each option grant is estimated using the Black-Scholes-Merton option pricing model. The fair value is then amortized on a straight-line basis over the requisite service period of the awards, which is generally the vesting period. Use of a valuation model requires management to make certain assumptions with respect to selected model inputs. Expected volatility is calculated based on an analysis of historic volatility of the Company's stock price. The average expected life is based on the contractual term of the option using the simplified method. The risk-free interest rate is based on U.S. Treasury

zero

-coupon issues with a remaining term equal to the expected life assumed at the date of grant. The compensation expense recognized is net of estimated forfeitures. Forfeitures are estimated based on actual share option forfeiture history.

The weighted-average assumptions used in the Black-Scholes-Merton option pricing model for

2018,

2017

and

2016

are as follows:

	201 8			201 7			201 6
Weighted average grant date fair value	$	17.86		$	16.84		$	13.77

Assumptions:
Expected stock price volatility		37	%		40	%		41	%
Risk free interest rate		2.60	%		1.92	%		1.31	%
Expected annual dividend per share	$	-		$	-		$	-
Expected life of options (years)		6.25			6.25			6.25

A summary of the Company’s stock option activity and related information for the years ended

December 31, 2018,

2017

and

2016

is as follows:

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value ($ in thousands)

Outstanding as of December 31, 2015A		2,128,014			15.15		7.7	$	40,271
Granted		398,313			33.24
Exercised		(995,469	)		2.89
Forfeited		(47,894	)		37.41
Outstanding as of December 31, 2016		1,482,964			27.49		7.5	$	23,840

Granted		346,421			40.13
Exercised		(287,375	)		10.58
Forfeited		(69,880	)		41.12
Outstanding as of December 31, 2017		1,472,130			33.11		7.3	$	25,281

Granted		366,231			43.88
Exercised		(267,909	)		19.90
Forfeited		(49,285	)		43.34
Outstanding as of December 31, 2018		1,521,167			37.70		7.0	$	19,212

Exercisable as of December 31, 2018		696,954			34.16		5.6	$	11,779

As of

December 31, 2018,

there was

$9,538

of total unrecognized compensation cost, net of expected forfeitures, related to unvested options. The cost is expected to be recognized over the remaining service period, having a weighted-average period of

2.5

years. Total share-based compensation cost related to the stock options for

2018,

2017

and

2016

was

$4,998,

$4,503

and

$4,366,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.

Restricted Stock

– Restricted stock awards vest in equal installments over

three

years, subject to the grantee’s continued employment or service. Certain restricted stock awards also include performance shares, which were awarded in the years

2014

through

2018.

The number of performance shares that can be earned are contingent upon Company performance measures over a

three

-year period. Performance measures are based on a weighting of revenue growth and EBITDA margin, from which grantees

may

earn from

200%

of their target performance share award. The performance period for the

2016

awards covers the years

2016

through

2018,

the performance period for the

2017

awards covers the years

2017

through

2019,

and the performance period for the

2018

awards covers the years

2018

through

2020.

The Company estimates the number of performance shares that will vest based on projected financial performance. The fair value of restricted awards is determined based on the market value of the Company's shares on the grant date. The fair market value of the restricted awards at the time of the grant is amortized to expense over the period of vesting. The compensation expense recognized for restricted share awards is net of estimated forfeitures.

Restricted stock vesting is net-share settled such that, upon vesting, the Company withholds shares with value equivalent to the employees’ minimum statutory tax obligation, and then pays the cash to the taxing authorities on behalf of the employees. In effect, the Company repurchases these shares and classifies them as treasury stock. Total shares withheld were

38,186,

39,500

and

28,593

2018,

2017

and

2016,

respectively, and were based on the value of the stock on the vesting dates. Total payments made by the Company for the employees’ tax obligations to the taxing authorities were

$1,812,

$1,591

and

$952

2018,

2017

and

2016,

respectively, and are reflected as a financing activity within the consolidated statements of cash flows.

A summary of the Company's restricted stock activity for the years ended

December 31, 2018,

2017

and

2016

is as follows:

	Shares			Weighted- Average Grant- Date Fair Value

Non-vested as of December 31, 2015		243,040			44.16
Granted		232,295			33.56
Vested		(95,858	)		41.93
Forfeited		(18,074	)		38.30
Non-vested as of December 31, 2016		361,403			38.18

Granted		211,769			39.91
Vested		(133,796	)		40.60
Forfeited		(47,100	)		42.48
Non-vested as of December 31, 2017		392,276			37.77

Granted		208,803			44.49
Vested		(128,433	)		39.03
Forfeited		(46,650	)		39.43
Non-vested as of December 31, 2018		425,996			40.50

As of

December 31, 2018,

there was

$9,210

of unrecognized compensation cost, net of expected forfeitures, related to non-vested restricted stock awards. That cost is expected to be recognized over the remaining service period, having a weighted-average period of

1.8

years. Total share-based compensation cost related to the restricted stock for

2018,

2017

and

2016,

inclusive of performance shares, was

$9,565,

$5,702

and

$5,127,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.

During

2018,

2017

and

2016,

33,419,

34,095

and

19,326

shares, respectively, of stock were granted to certain members of the Company’s Board of Directors as a component of their compensation for their service on the Board, of which

33,419,

22,762

and

19,326

shares, respectively, were fully vested. Total share-based compensation cost for these share grants in

2018,

2017

and

2016

was

$1,718,

$1,133

and

$670,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.