Share Based Compensation, 401(k) Plan and Deferred Compensation (Restricted Share Activity) (Details) (Restricted Share Awards [Member], USD $)	12 Months Ended
	Dec. 31, 2011
Restricted Share Awards [Member]
Company's restricted share activity
Non-vested at January 1, 2011, shares	851,278
Non-vested at January 1, 2011, Weighted Average Grant Date Fair value	$ 10.75
Granted, shares	197,035
Granted, Weighted Average Grant Date Fair value	$ 11.92
Vested, shares	(237,541)
Vested, Weighted Average Grant Date Fair value	$ 19.76
Forfeited, shares	(3,481)
Forfeited, Weighted Average Grant Date Fair Value	$ 11.47
Non-vested at December 31, 2011, shares	807,291
Non-vested at December 31, 2011, Weighted Average Grant Date Fair value	$ 9.46