The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 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_UnrealizedGainLossOnDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 May 9, 2016 [Member] Swap [Member]	Dec. 31, 2012 May 9, 2016 [Member] Swap [Member]	Jul. 31, 2011 May 9, 2016 [Member] Swap [Member]	Jun. 30, 2013 June 30, 2017 [Member] Swap [Member]	Jun. 29, 2013 June 30, 2017 [Member] Swap [Member]
Derivative [Line Items]
Stated Interest Rate				2.02%			1.1825%
Net gain on derivative instruments	$ (452)	$ (742)	$ (662)
Notional Amount				69,375	72,188	75,000	65,625	65,600
Market Value (Liability)				$ (2,243)	$ (3,146)		$ (161)