Fair Value Measurements (Details 2) (Negative arbitrage derivative, USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Jun. 30, 2013
Negative arbitrage derivative
Activity for Level 3 financial liability
Beginning balance		$ 12,865
Enhanced equipment trust certificates activity	12,865
Ending balance	$ 12,865	$ 12,865

Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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)(2)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

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