Stock Repurchase (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended
Nov. 30, 2010 November 29, 2010 Program [Member]	Jun. 30, 2012 November 29, 2010 Program [Member]	Jun. 30, 2012 November 29, 2010 Program [Member]	Dec. 31, 2011 November 29, 2010 Program [Member]	Dec. 31, 2010 November 29, 2010 Program [Member]	May 31, 2012 May 29, 2012 Program [Member]	Jun. 30, 2012 May 29, 2012 Program [Member]
Stock Repurchase (Textual) [Abstract]
Common stock repurchased and retired		337,366	337,366	265,040	65,000		0
Weighted average repurchase price of common stock		$ 14.66	$ 14.66	$ 16.00	$ 11.91
Maximum amount of common stock approved to repurchase, Value	$ 10.0					$ 20.0

Number of shares that have been repurchased and retired during the period.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Name:	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration