Financial Derivative Instruments (Summary of the hedging relationships) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Gross [Member]
Derivative [Line Items]
Unrealized losses on interest rate caps	$ (1,111)
Unamortized premium on interest rate caps	4,566
Total	3,455
Net of Tax [Member]
Derivative [Line Items]
Unrealized losses on interest rate caps	(722)
Unamortized premium on interest rate caps	2,968
Total	$ 2,246

The amount of debt premium that was originally recognized at the issuance of the instrument that has yet to be amortized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentUnamortizedPremium
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant