Derivatives (Details 4) (USD $) In Thousands, unless otherwise specified			3 Months Ended
Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Mark-to-Market on Series F Agreement [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mark-to-Market of the Series F Agreement			$ 416
Reconciliation of liabilities classified as Level 3
Ending liability balance	(1,251)	(1,667)
Total unrealized gains:
Ending liability balance	$ (1,251)	$ (1,667)

This item represents the amount of the total realized and unrealized gains or losses for the period which are included in the statement of income (or changes in net assets); the fair value of which assets and liabilities was or is measured on a recurring basis using significant unobservable inputs (Level 3).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration