Share Options And Awards (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option and share awards outstanding	4,790,828		4,790,828		4,614,272
Net compensation expense for share options and restricted shares	$ 1.4	$ 1.3	$ 4.9	$ 3.7
Net capitalized compensation expense	0.3	0.3	1.1	0.9
Period of historical data used to estimate volatility (years)			10
Award fair value assumptions and methods			The fair value of share options and restricted shares is estimated on the date of grant using the Black-Scholes option pricing method based on the expected weighted average assumptions in the following table. The dividend yield is an average of the historical yields at each record date over the estimated expected life. We estimate volatility using our historical volatility data for a period of 10 years, and the expected life is based on historical data from an option valuation model of employee exercises and terminations. The risk-free rate is based on the U.S. Treasury yield curve.
Share Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of option award, years			10
Total intrinsic value of options exercised	0.3	0.2	1.8	0.9
Unrecognized compensation cost	4.3		4.3		3.8
Weighted average expected amortization period for unrecognized compensation cost (years)			2.3		2.5
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate price of award			restricted shares for officers and trust managers are granted at no purchase price.
Unrecognized compensation cost	$ 5.7		$ 5.7		$ 5.1
Weighted average expected amortization period for unrecognized compensation cost (years)			2.6		2.8
LT Incentive Plan Stock Options And Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option and share awards outstanding	3,600,000		3,600,000
LT Incentive Plan Stock Options And Awards [Member] | Non-Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (years) for share options and awards			three
LT Incentive Plan Stock Options And Awards [Member] | Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (years) for share options and awards			five
2010 Restated LT Incentive Plan Stock Options and Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Plan expiration date			May 2020
Plan common shares authorized	3,000,000		3,000,000
Plan common shares available for future grants	2,100,000		2,100,000
2010 Restated LT Incentive Plan Stock Options and Awards [Member] | Non-Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (years) for share options and awards			three
2010 Restated LT Incentive Plan Stock Options and Awards [Member] | Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (years) for share options and awards			five