Commitments and contingencies - Litigation (Details) - Rosen v. Spirit Airlines and Legg v. Spirit Airlines [Member]	1 Months Ended
Aug. 31, 2014 case
Loss Contingencies [Line Items]
Number of cases filed	2
Previously certified as class action [Member]
Loss Contingencies [Line Items]
Number of cases filed	1

The total number of new claims filed pertaining to a loss contingency during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration