Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2010 Options 2010 [Member] years	Dec. 31, 2008 Options 2008 [Member] years
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Recognized Compensation Expense Average Period			5.0	3.6
Recognized Compensation Expense	$ 346	$ 346
Unrecognized Compensation Costs	3,409
Share Based Compensation Expense Relating to Scheduled Vesting and Issuance of Common Share Grants	$ 750	$ 472

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph i

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Name:	us-gaap_StockOptionPlanExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration