Leases - Narrative (Details) $ in Millions	3 Months Ended
Sep. 30, 2017 USD ($)
Leases [Abstract]
Airplane operating lease period	7 years
Maximum residual value guarantee	$ 11.1
Fair value of residual value guarantee, fair value of operating lease asset, threshold	$ 14.4

Amount of residual asset covered by residual value guarantee under operating lease. Excludes guarantee considered to be lease payments for lessor.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)(3)
-URI https://asc.fasb.org/extlink&oid=124258985&loc=SL77919359-209981

Name:	us-gaap_OperatingLeaseResidualValueOfLeasedAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant