Nature of Operations, Basis of Presentation, and Summary of Significant Accounting Policies (Narrative) (Details)	Jun. 30, 2019
North Shore Aviation Holdings LLC [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	27.50%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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