Advances Receivable, net - Additional Information (Details) - USD ($)	6 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2020
Measure of concentration	100.00%		100.00%
Collection in advance	$ 5,000,000	$ 3,000,000
Aviation advance [Member]
Cash advances	$ 9,000,000	$ 8,000,000

The cash inflow associated with principal collections from a borrowing supported by a written promise to pay an obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromCollectionOfNotesReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration