CAPITAL STOCK AND STOCK AWARD PLANS (Tables)

12 Months Ended

Dec. 31, 2018

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

Schedule of Stock-Based Compensation Expense

A summary of our total compensation expense recognized in our consolidated statements of operations and comprehensive income for stock-based compensation is as follows (in thousands):

	2018		2017		2016
Stock options	$	23,374	$	10,109	$	9,178
Stock awards	61,826		29,217		25,912
Company expense on ESPP discount	2,591		2,479		2,475
Total stock-based compensation expense	$	87,791	$	41,805	$	37,565

Schedule of Stock Option Activity

The following schedule summarizes stock option activity in the plans. All outstanding unvested options as of December 31, 2018, relate to performance-based grants from 2014 and time-based grants from 2015 through 2018.

	Options		Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Average Remaining Life (years)
Outstanding at December 31, 2017	7,382,072		$	71.58	$	129,295	7.6
Grants	1,074,665		88.92
Exercised	(578,467	)	65.13
Terminated	(55,756	)	73.92
Outstanding at December 31, 2018	7,822,514		$	74.42	$	85,222	7.2
Vested at December 31, 2018	4,191,118		$	68.35			5.9
Exercisable at December 31, 2018	4,191,118		$	68.35			5.9

Schedule of Intrinsic Value of Options Exercised

Information on the intrinsic value of options exercised is as follows (in thousands):

2018	$	16,209
2017	6,026
2016	981

Schedule of Performance Based Options by Vesting Period

The following table summarizes performance based options by vesting period:

First Vesting Date	Last Vesting Date	Options Granted, Net of Forfeitures	Weighted Average Grant Date Fair Value		Unvested Options
December 31, 2015	December 31, 2019	1,253,443	$	14.17	136,781

Schedule of Unvested Stock Option Grants

The following table summarizes these unvested stock option grants as of December 31, 2018:

First Vesting Date	Last Vesting Date	Options Granted, Net of Forfeitures	Weighted Average Grant Date Fair Value		Unvested Options
December 31, 2016	December 31, 2020	1,421,933	$	12.66	561,579
December 31, 2017	December 31, 2021	1,246,480	12.60		735,744
December 31, 2018	December 31, 2022	1,470,606	14.25		1,162,504
December 31, 2019	December 31, 2023	1,034,788	20.52		1,034,788
		5,173,807	$	14.67	3,494,615

Schedule of Option Pricing Model Valuation Assumptions

The fair value per option was estimated using the Black-Scholes option pricing model with the following assumptions:

	2018 Grants			2017 Grants			2016 Grants
Weighted-average risk-free interest rate	3.1		%	2.3		%	2.1		%
Expected dividend yield	2.0		%	2.5%			2.4%
Weighted-average volatility	25%			20%			20%
Expected term (in years)	6.08			6.20			6.26
Weighted average fair value per option	$	20.52		$	14.23		$	12.60

Schedule of Performance Based Restricted Shares and Restricted Stock Units

The following table summarizes our unvested performance based restricted shares and restricted stock unit grants as of December 31, 2018:

	Number of  Shares and Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	1,215,459		$	61.71
Granted	340,287		74.54
Vested	(687,463	)	60.14
Forfeitures	(22,113	)	60.50
Unvested at December 31, 2018	846,170		$	68.35

The following table summarizes performance based restricted shares and restricted stock units by vesting period:

First Vesting Date	Last Vesting Date	Performance Shares and Stock Units Granted, Net of Forfeitures	Weighted Average Grant Date Fair Value (1)		Unvested Performance Shares and Restricted Stock Units
December 31, 2015	December 31, 2019	323,442	$	61.75	34,572
December 31, 2016	December 31, 2020	389,644	51.88		139,431
December 31, 2017	December 31, 2021	339,808	64.91		162,955
December 31, 2018	December 31, 2022	312,797	74.26		178,294
December 31, 2019	December 31, 2023	330,918	74.48		330,918
		1,696,609	$	64.91	846,170

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⁽¹⁾  Amount shown is the weighted average grant date fair value of performance shares and restricted stock units granted, net of forfeitures.

Schedule of Unvested Restricted Share and Restricted Stock Unit Grants

The following table summarizes these unvested restricted share and restricted stock unit grants as of December 31, 2018:

	Number of Restricted Shares and Stock Units		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	1,057,450		$	62.20
Granted	279,679		74.54
Vested	(324,965	)	58.46
Forfeitures	(85,472	)	62.57
Unvested at December 31, 2018	926,692		$	67.08

Schedule of Fair Value Stock Awards Vested

A summary of the fair value of full value awards vested (in thousands):

2018	$	61,826
2017	29,217
2016	25,912

Schedule of Employee Stock Purchase Plan Activity

The following is a summary of the employee stock purchase plan activity (dollar amounts in thousands):

	Shares Purchased By Employees	Aggregate Cost to Employees		Expense Recognized By the Company
2018	191,823	$	14,682	$	2,591
2017	215,613	14,048		2,479
2016	225,241	14,032		2,475

Schedule of Share Repurchase Program Activity

The activity under these authorizations is as follows (dollar amounts in thousands):

	Shares Repurchased	Total Value of Shares Repurchased
2016 Repurchases	2,467,097	$	176,676
2017 Repurchases	2,426,407	179,985
2018 Repurchases	3,319,077	303,492