Stock-Based Compensation Plans (Tables)

3 Months Ended

Mar. 31, 2018

A summary of the Company's stock option activity for the three months ended March 31, 2018 and March 31, 2017 is presented below:



Stock Options	Common Shares		Weighted Average Strike Price		Remaining Contractual Term⁽¹⁾	Intrinsic Value ⁽²⁾ ($000)
Outstanding at January 1, 2018	1,084,756		$	41.98
Granted	—		—
Exercised	(169,387	)	42.47
Forfeited or canceled	(1,703	)	40.87
Outstanding at March 31, 2018	913,666		$	41.89	3.7	$	40,351
Exercisable at March 31, 2018	712,535		$	42.00	3.4	$	31,391



Stock Options	Common Shares		Weighted Average Strike Price		Remaining Contractual Term ⁽¹⁾	Intrinsic Value ⁽²⁾ ($000)
Outstanding at January 1, 2017	1,698,912		$	41.50
Granted	—		—
Exercised	(319,802	)	39.97
Forfeited or canceled	(6,496	)	42.65
Outstanding at March 31, 2017	1,372,614		$	41.85	4.6	$	37,436
Exercisable at March 31, 2017	819,955		$	41.60	4.0	$	22,568


(1)	Represents the remaining weighted average contractual life in years.

(2)

Aggregate intrinsic value represents the total pre-tax intrinsic value (i.e., the difference between the Company's stock price on the last trading day of the quarter and the option exercise price, multiplied by the number of shares) that would have been received by the option holders if they had exercised their options on the last day of the quarter. Options with exercise prices above the stock price on the last trading day of the quarter are excluded from the calculation of intrinsic value. The intrinsic value will change based on the fair market value of the Company's stock.

Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity

A summary of the Plans' restricted share activity for the three months ended March 31, 2018 and March 31, 2017 is presented below:



	Three months ended March 31, 2018				Three months ended March 31, 2017
Restricted Shares	Common Shares		Weighted Average Grant-Date Fair Value		Common Shares		Weighted Average Grant-Date Fair Value
Outstanding at January 1	127,787		$	53.33	133,425		$	49.94
Granted	20,700		86.42		8,425		72.52
Vested and issued	(7,258	)	53.47		(5,063	)	42.71
Forfeited or canceled	(982	)	55.39		—		—
Outstanding at March 31	140,247		$	58.20	136,787		$	51.60
Vested, but not issuable at March 31	89,924		$	51.71	89,215		$	51.51

A summary of the Plans' performance-based stock award activity, based on the target level of the awards, for the three months ended March 31, 2018 and March 31, 2017 is presented below:



	Three months ended March 31, 2018				Three months ended March 31, 2017
Performance-based Stock	Common Shares		Weighted Average Grant-Date Fair Value		Common Shares		Weighted Average Grant-Date Fair Value
Outstanding at January 1	359,196		$	54.37	298,180		$	43.64
Granted	127,419		88.20		141,399		72.55
Vested and issued	(82,307	)	44.39		(68,712	)	46.85
Forfeited	(6,580	)	49.42		(7,731	)	50.11
Outstanding at March 31	397,728		$	67.35	363,136		$	54.15
Vested, but deferred at March 31	21,388		$	43.32	13,564		$	42.55