Noncontrolling Interests (Details Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Noncontrolling Interests (Textual) [Abstract]
Ownership interest percentage to consolidate partnerships	50.10%
Net income attributable to noncontrolling interests	$ 5,245	$ 5,411	$ 5,165

Amount of Net Income (Loss) attributable to noncontrolling interest.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4J

-URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4591551-111686

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration