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Compensation Programs (Narrative) (Details) (USD $)	6 Months Ended	12 Months Ended		6 Months Ended			3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
Compensation Programs (Narrative) (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2009	Dec. 31, 2010	Jun. 30, 2011 2008 [Member] Performance Based Stock Awards [Member]	Jun. 30, 2011 2009 [Member] Performance Based Stock Awards [Member]	Jun. 30, 2011 2010 [Member] Performance Based Stock Awards [Member]	Jun. 30, 2011 Annual Incentive Compensation [Member]	Jun. 30, 2011 Annual Incentive Compensation [Member]	Dec. 31, 2010 Annual Incentive Compensation [Member]	Jun. 30, 2011 Stock Awards Activity [Member]	Jun. 30, 2011 Stock Awards Activity [Member]	Jun. 30, 2011 Long Term Equity Based Awards [Member]	Jun. 30, 2011 Option Awards [Member]	Jun. 30, 2011 Option Awards [Member]	Jun. 30, 2011 Other Benefit Programs [Member]	Jun. 30, 2011 Other Benefit Programs [Member]
Expenses related to compensation							$ 1,500,000	$ 2,700,000		$ 453,000	$ 880,000		$ 1,000	$ 3,000	$ 131,000	$ 243,000
Expiration date of grant	July 1, 2013			2015	2016	2017
Common shares for future issuance	1,180,441
Percentage of investment capital, maximum	10.00%							10.00%	8.00%			8.00%
No of years for average long-term investment capital								10				10
Spread over 10-year U.S. treasury rate (basis points)								200				200
Share awards vesting period (in years)												three		ten
Common stock dividend payable	39,132,000		27,401,000							164,000	164,000
Weighted average remaining contractual term											1.7			5.82
Total of unrecognized compensation costs for unvested option awards										4,000,000	4,000,000
Strike price		$ 11.69
Grant date fair value per share		$ 1.52
Volatility factors for years		51.00%
Dividend yields for years		14.00%
Risk free rates for years		$ 1.70%
Exercisable option awards exercised to date													281,250	281,250
Weighted average exercise price													$ 10.51	$ 10.51
Aggregate intrinsic value of stock options													824,000	824,000
Intrinsic value of stock options exercised													$ 9,000	$ 25,000
Compensation plan of voluntary contribution																50.00%
Compensation plan of voluntary contribution, maximum																6.00%
Compensation plan of voluntary contribution, minimum																3.00%