Benefit Plans (Details) (USD $)	12 Months Ended							12 Months Ended		12 Months Ended										12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Share Options [Member]	Dec. 31, 2011 Share Options [Member]	Dec. 31, 2010 Share Options [Member]	Dec. 31, 2009 Share Options [Member]	Dec. 31, 2010 2010 Options [Member]	Dec. 31, 2012 2010 Options [Member]	Dec. 31, 2012 2009 Options [Member] years	Jan. 08, 2010 2009 Options [Member]	Dec. 31, 2012 2008 Options [Member] years days	Dec. 31, 2010 2008 Options [Member]	Dec. 31, 2008 2008 Options [Member]	Dec. 31, 2012 Non-vested Shares [Member]	Dec. 31, 2011 Non-vested Shares [Member]	Dec. 31, 2010 Non-vested Shares [Member]	Dec. 31, 2012 Shares Subject to Time [Member]	Dec. 31, 2012 Shares Subject to Performance [Member]	Dec. 31, 2012 Share Based Compensation Arrangement By Share Based Payment Award Vesting Rate First Vesting Trigger [Member] 2008 Options [Member]	Dec. 31, 2012 Minimum [Member] 2008 Options [Member]	Dec. 31, 2012 Maximum [Member] 2008 Options [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number															1,465,446	1,179,585	819,577	1,092,306	373,140
Common Share Options Granted								1,248,501			1,265,500			2,000,000
Common Share Options Exercise Price				$ 6.44	$ 6.36	$ 6.23	$ 4.97	$ 7.95			$ 6.39			$ 5.60
Share Based Compensation Arrangement By Share Based Payment Award Vesting Rate				20.00%						20.00%										50.00%
Number Of Trading Period Days Where Entitys Average Closing Price Per Common Share Is Greater Than The Stated Lower Amount Triggering Vesting												20
Stated Lower Amount Where Entitys Average Closing Price Per Common Share Is Greater Than The Stated Amount Trigerring																					$ 8.00	$ 10.00
Share Based Compensation Arrangement by Share Based Payment Award Options Convertible To Common Shares												1.13
Options Converted To Common Shares Exercise Price												$ 4.97
Deferred Compensation Equity									$ 2,422,000	$ 2,771,000		$ 2,480,000
Recognized Compensation Expense Average Period										5.0		3.6
Recognized Compensation Expense	1,197,000	1,384,000	1,824,000
Stock or Unit Option Plan Expense Due to Accelerated Vesting													629,000
Unrecognized Compensation Costs				2,559,000											9,648,000
Options exercised in period, intrinsic value	1,603,000	2,100,000	1,145,000
Options, exercisable, intrinsic value	3,930,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant															4,437,962
Common Stock Held in Trust	427,531	427,531
Initial Vesting Percentage	25.00%
Vesting Percentage	100.00%
Defined Contribution Plan, Cost Recognized	279,000	308,000	311,000
Allocated Share-based Compensation Expense	$ 3,030,000	$ 2,062,000	$ 3,232,000