Revolving Credit Facility - Narrative (Details) - USD ($)	3 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019
Line Of Credit Facility [Line Items]
Revolving credit facility outstanding amount	$ 57,900,000		$ 34,650,000
Revolving credit facility, description of variable rate basis	one month LIBOR
Amortization of financing fees	$ 54,000	$ 79,000
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Term of credit facility (in years)	5 years
Maximum borrowing capacity	$ 180,000,000
Revolving credit facility maturity date	Jan. 29, 2024
Availability to be maintained under credit facility	$ 12,500,000
Availability to be maintained under credit facility before restriction on investments, percentage	20.00%
Covenant terms	The Revolving Credit Facility requires that we satisfy a fixed charge coverage ratio at any time that our availability is less than the greater of 10% of our calculated borrowing base of $12.5 million.
Revolving credit facility outstanding amount	$ 57,900,000
Outstanding letters of credit	8,900,000
Availability under the credit facility	$ 65,300,000
Frequency of commitment fee payment	Payable quarterly
Interest expense	$ 700,000	600,000
Commitment fees	100,000	100,000
Interest expense, debt	500,000	400,000
Amortization of financing fees	$ 100,000	$ 100,000
Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Availability to be maintained under credit facility, percentage	10.00%
Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Commitment fees (as a percent)	0.25%