Stock Based Compensation (Restricted Stock) (Details) (USD $)	3 Months Ended																				12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2009	Jun. 30, 2009	Mar. 31, 2009	Dec. 31, 2008	Sep. 30, 2008	Jun. 30, 2008	Mar. 31, 2008	Sep. 30, 2005	Jun. 30, 2005	Jun. 30, 2004	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2006	Dec. 31, 2009 Non-Employee Directors [Member]	Dec. 31, 2008 Non-Employee Directors [Member]	Dec. 31, 2007 Non-Employee Directors [Member]	Dec. 31, 2008 Employee [Member]	Dec. 31, 2007 Employee [Member]	Dec. 31, 2006 Employee [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Incentive restricted stock issued	10,000																	54,806	54,806	319,300	91,364	209,358	16,536	12,224	80,676	14,464	33,000	66,000	57,500
Exercise price																				$ 0
Percent of shares issued	20.00%	20.00%	20.00%	20.00%	20.00%	25.00%	25.00%	25.00%	25.00%	25.00%	25.00%	25.00%	25.00%	40.00%	30.00%	20.00%	10.00%
Percentage of shares vested		25.00%	25.00%	25.00%	25.00%
Shares granted exercise price	$ 0
Performance restricted stock issued																							153,500