Equity Incentive Plans (Summary Of Share Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands | 6 Months Ended | | |
Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017 | May 12, 2016 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period | 5,742 | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price | $ 52.42 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Non-employee Trustee Length of Period Subsequent to Grant Date Options Not Exercisable | 1 year | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 5 years 1 month | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 4 years 9 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 228,820 | | | |
Maximum term of options granted (in years) | 10 years | | | |
Exercisable rate for employees options, per year | 25.00% | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at Beginning of Period | 257,606 | | | |
Number of Shares, Granted | 3,835 | | | |
Number of Shares, Outstanding at End of Period | 255,494 | | | |
Average Exercise Price, Outstanding at Beginning of Period | $ 51.87 | | $ 51.81 | |
Average Exercise Price, Outstanding at End of Period | 51.87 | | 51.81 | |
Weighted average fair value of options granted | $ 3.03 | $ 7.91 | | |
Intrinsic value of stock options exercised | $ 100 | $ 500 | | |
Share based compensation expenses recognized in future periods | $ 200 | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ 56.94 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period | 205 | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price | $ 59.02 | | | |
Minimum [Member] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period, Price Per Share | 51.64 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Price Per Share | 45.20 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Option Price Per Share, Outstanding at Beginning of Period | 19.02 | | 19.02 | |
Option Price Per Share, Outstanding at End of Period | 19.02 | | 19.02 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Price Per Share | 56.94 | | | |
Maximum [Member] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period, Price Per Share | 61.79 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Price Per Share | 61.79 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Option Price Per Share, Outstanding at Beginning of Period | 76.63 | | 76.63 | |
Option Price Per Share, Outstanding at End of Period | 76.63 | | $ 76.63 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Price Per Share | $ 56.94 | | | |
Share Options [Member] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Stock-option expense | $ 147 | $ 361 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum | 2.70% | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate | 18.90% | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Forfeiture Rate | 0.74% | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term | 6 years | | | |
Share Options [Member] | Minimum [Member] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate | 7.60% | | | |
2016 Equity Incentive Plan [Member] | | | | |
Common shares, options to purchase common shares and restricted share units, expected to granted (in shares) | | | | 1,950,000 |
Number of shares available for grant (in shares) | 1,309,271 | | | |
Exercise Price Range Nineteen Point Two to Nineteen Point Nine Nine [Member] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 11 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 11 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 11,097 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at End of Period | 11,097 | | | |
Thirty To Thirty Nine Point Nine Nine Member | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 1 year 6 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 1 year 6 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 1,428 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at End of Period | 1,428 | | | |
Forty To Forty Nine Point Nine Nine Member | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 3 years 7 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 3 years 7 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 84,509 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at End of Period | 84,509 | | | |
Fifty To Fifty Nine Point Nine Nine Member | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 5 years 8 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 5 years 6 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 72,639 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at End of Period | 76,474 | | | |
Sixty To Sixty Five Point Five Zero Member | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 6 years 7 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 6 years 7 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 58,593 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at End of Period | 79,771 | | | |
Seventy To Seventy Six Point Six Three [Member] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 8 years 8 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 8 years 8 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 554 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] | | | | |
Number of Shares, Outstanding at End of Period | 2,215 | | | |