Equity Incentive Plans (Summary Of Share Option Activity) (Details) (USD $)	3 Months Ended		9 Months Ended	144 Months Ended		3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2012	Dec. 31, 2008	Dec. 31, 2012	Mar. 31, 2013 Minimum [Member]	Sep. 30, 2012 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Sep. 30, 2012 Maximum [Member]	Dec. 31, 2012 Maximum [Member]	Mar. 31, 2013 Share Options [Member]	Mar. 31, 2012 Share Options [Member]	Mar. 31, 2012 Share Options [Member] Minimum [Member]	Mar. 31, 2013 Share Options [Member] Maximum [Member]	Mar. 31, 2012 Share Options [Member] Maximum [Member]	Mar. 31, 2013 2007 Equity Incentive Plan [Member]	May 09, 2007 2007 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)																	267,658
Maximum term of options granted (in years)	10 years
Share based compensation, future vesting period minimum (in years)	4 years			5 years			3 years			4 years		4 years
Exercisable rate for employees options, per year	25.00%
Length of period subsequent to grant date options not exercisable for non-employee trustees (in years)	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares, Outstanding at Beginning of Period	881,338
Number of Shares, Exercised	(75,399)
Number of Shares, Granted	107,757
Number of Shares, Forfeited	(2,658)
Number of Shares, Outstanding at End of Period	911,038
Option Price Per Share, Outstanding at Beginning of Period						$ 18.18		$ 18.18	$ 65.50		$ 65.50
Option Price Per Share, Exercised						$ 18.18			$ 47.20
Option Price Per Share, Granted						$ 46.86			$ 47.21
Option Price Per Share, Forfeited						$ 36.56			$ 46.69
Option Price Per Share, Outstanding at End of Period						$ 18.18		$ 18.18	$ 65.50		$ 65.50
Average Exercise Price, Outstanding at Beginning of Period	$ 40.72				$ 38.51
Average Exercise Price, Exercised	$ 23.89
Average Exercise Price, Granted	$ 47.15
Average Exercise Price, Forfeited	$ 43.65
Average Exercise Price, Outstanding at End of Period	$ 40.72				$ 38.51
Weighted average fair value of options granted	$ 12.05	$ 11.98
Intrinsic value of stock options exercised		$ 1,300,000	$ 1,900,000
Repurchase of treasury stock (in shares)	50,583
Repurchase of treasury stock, value	2,500,000
Share based compensation expenses recognized in future periods	2,300,000
Stock-option expense												$ 222,000	$ 256,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum												1.00%	1.10%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum													1.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate														6.40%	6.50%	6.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate												50.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum														50.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum																51.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Forfeiture Rate	0.23%	0.25%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term												6 years