CAPITAL STOCK AND STOCK AWARD PLANS (Tables)

12 Months Ended

Dec. 31, 2017

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

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

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):

	2017		2016		2015
Stock options	$	10,109	$	9,178	$	14,607
Stock awards	29,217		25,912		40,785
Company expense on ESPP discount	2,479		2,475		2,269
Total stock-based compensation expense	$	41,805	$	37,565	$	57,661

Schedule of Share-based Compensation, Stock Options, Activity

The following schedule summarizes stock option activity in the plans. All outstanding unvested options as of December 31, 2017, relate to performance-based grants from 2013 and 2014 and time-based grants from 2015 through 2017.

	Options		Weighted Average Exercise Price		Aggregate Intrinsic Value (in thousands)		Average Remaining Life (years)
Outstanding at December 31, 2016	7,007,923		$	67.00	$	43,875	7.7
Grants	1,452,765		87.11
Exercised	(388,135	)	63.81
Terminated	(690,481	)	62.17
Outstanding at December 31, 2017	7,382,072		$	71.58	$	129,295	7.6
Vested at December 31, 2017	2,990,514		$	65.79			6.3
Exercisable at December 31, 2017	2,990,514		$	65.79			6.3

Schedule of Intrinsic Value of Options Exercised

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

2017	$	6,026
2016	981
2015	400

Schedule of Share-based Compensation, Activity

The following table summarizes these unvested stock option grants as of December 31, 2017:

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	1,423,053	$	12.66	855,984
December 31, 2017	December 31, 2021	1,253,169	$	12.60	1,003,429
December 31, 2018	December 31, 2022	1,446,070	$	14.24	1,446,070
		4,122,292	$	13.20	3,305,483

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, 2014	December 31, 2018	387,587	$	46.50	109,784
December 31, 2015	December 31, 2019	329,596	60.80		175,904
December 31, 2016	December 31, 2020	392,990	51.88		309,300
December 31, 2017	December 31, 2021	343,014	64.91		312,142
December 31, 2018	December 31, 2022	308,329	74.19		308,329
		1,761,516	$	58.71	1,215,459

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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.

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, 2014	December 31, 2018	1,412,773	11.83		403,149
December 31, 2015	December 31, 2019	1,271,223	14.17		682,926
		2,683,996	$	12.94	1,086,075

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

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

	2017 Grants		2016 Grants		2015 Grants
Risk-free interest rate	2.27-2.28%		2.13-2.14%		1.95-1.96%
Dividend per share (quarterly amounts)	$0.45-0.46		$0.43-0.45		$0.38-0.43
Expected volatility factor	19.0-21.5%		20.0-21.5%		22.0-24.0%
Expected option term	6.20 years		6.26 years		6.29 years
Weighted average fair value per option	$	14.23	$	12.60	$	12.68

Schedule of Nonvested Restricted Stock Units Activity

The following table summarizes our unvested performance based restricted shares and restricted stock unit grants as of December 31, 2017:

	Number of  Shares and Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested at December 31, 2016	1,245,175		$	55.90
Granted	310,071		74.14
Vested	(121,030	)	55.77
Forfeitures	(218,757	)	49.51
Unvested at December 31, 2017	1,215,459		$	61.71

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following table summarizes these unvested restricted share and restricted stock unit grants as of December 31, 2017:

	Number of Restricted Shares and Stock Units		Weighted Average Grant Date Fair Value
Unvested at December 31, 2016	1,240,156		$	56.70
Granted	280,097		74.17
Vested	(386,859	)	54.39
Forfeitures	(75,944	)	56.41
Unvested at December 31, 2017	1,057,450		$	62.20

Schedule Of Fair Value Stock Awards Vested

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

2017	$	29,217
2016	25,912
2015	40,785

Schedule of Share-based Compensation, 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
2017	215,613	$	14,048	$	2,479
2016	225,241	14,032		2,475
2015	228,103	13,045		2,269

Share Repurchase Program Disclosure

The activity under this authorization is as follows (dollar amounts in thousands):

	Shares Repurchased	Total Value of Shares Repurchased
2013 Program
2013 Repurchases	930,075	$	57,689
2014 Repurchases	3,763,583	239,037
2015 Repurchases	3,420,681	232,113
2016 Repurchases	2,467,097	176,676
2017 Repurchases	2,426,407	179,985