Summary of Significant Accounting Policies (Details Textual) (USD $) In Millions, unless otherwise specified			6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Cash, Cash Equivalents and Marketable Securities [Member] Maximum [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract
Deferred offering costs in other assets	$ 0.8	$ 0
Summary of Significant Accounting Policies (Textual) [Abstract]
Highly liquid investments maturity period			90 days

Specific incremental costs directly attributable to a proposed or actual offering of securities which are deferred at the end of the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.8)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 340

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6955238&loc=d3e105025-122735

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section A

Name:	us-gaap_DeferredOfferingCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant