Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2017

Share-based Compensation [Abstract]

Summary Of Share Option Activity

A summary of the Company’s share option activity and related information is as follows:

	Number of shares		Option price per share					Weighted avg. exercise price
Outstanding at December 31, 2014	950,214		$	18.18	—	$	65.50	$	42.48
Exercised	(476,400	)	18.18		—	61.53		37.42
Granted	121,546		61.79		—	61.79		61.79
Forfeited	(79,055	)	45.20		—	65.50		63.88
Outstanding at December 31, 2015	516,305		$	19.02	—	$	65.50	$	48.42
Exercised	(230,319	)	19.41		—	65.50		44.05
Outstanding at December 31, 2016	285,986		$	19.02	—	$	61.79	$	51.93
Exercised	(29,253	)	46.86		—	61.79		54.54
Granted	2,215		76.63		—	76.63		76.63
Forfeited/Expired	(1,342	)	51.64		—	61.79		59.52
Outstanding at December 31, 2017	257,606		$	19.02	—	$	76.63	$	51.81

Schedule of Stock Option Expense to be Recognized in the Future

At December 31, 2017, stock-option expense to be recognized in future periods was as follows (in thousands):

	Amount
Year:
2018	$	291
2019	4
2020	4
Total	$	299

Summary Of Outstanding Options

The following table summarizes outstanding options at December 31, 2017:

Exercise price range	Options outstanding	Weighted avg. life remaining	Weighted avg. exercise price		Aggregate intrinsic value  (in thousands)
$ 19.02 - 19.99	11,097	1.4
20.00 - 29.99	—	—
30.00 - 39.99	1,428	2.0
40.00 - 49.99	86,041	4.1
50.00 - 59.99	75,939	5.8
60.00 - 69.99	80,886	7.1
70.00 - 76.63	2,215	9.1
	257,606	5.5	$	51.81	$	3,541

Summary Of Exercisable Options

The following table summarizes exercisable options at December 31, 2017:

Exercise price range	Options outstanding	Weighted avg. life  remaining	Weighted avg. exercise price		Aggregate  intrinsic value (in thousands)
$ 19.02 - 19.99	11,097	1.4
20.00 - 29.99	—	—
30.00 - 39.99	1,428	2.0
40.00 - 49.99	86,041	4.1
50.00 - 59.99	51,276	5.7
60.00 - 61.79	38,225	7.1
70.00 - 76.63	—	—
	188,067	5.0	$	49.28	$	3,044

Summary Of Nonvested Share Activity

A summary of the Company’s nonvested share activity and related information is as follows:

	Number  of shares		Weighted avg. grant  date fair value		Weighted avg. life remaining
Outstanding at December 31, 2016	534,317		$	59.22
Granted	296,914		76.49
Vested	(209,767	)	57.47
Forfeited	(1,342	)	66.88
Outstanding at December 31, 2017	620,122		$	68.07	0.96

Nonvested Shares Unamortized Share-based Compensation Expense to be Recognized in the Future

At December 31, 2017, unamortized share-based compensation expense related to nonvested shares was $21.2 million and will be recognized in future periods as follows (in thousands):

	Amount
Year:
2018	$	10,391
2019	7,337
2020	3,445
Total	$	21,173

Summary Of Restricted Share Unit Activity

A summary of the Company’s restricted share unit activity and related information is as follows:

	Number  of Shares		Weighted Average Grant Date Fair Value		Weighted Average Life Remaining
Outstanding at December 31, 2016	15,805		$	70.93
Granted	19,030		70.91
Vested	(15,805	)	70.93
Outstanding at December 31, 2017	19,030		$	70.91	0.33