Nature of Business and Summary of Significant Accounting Policies - Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Jun. 30, 2017
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, Cost	$ 15,700	$ 15,700
Finite-lived intangible assets, Accumulated amortization	(7,969)	(7,784)
Finite-lived intangible assets, Net book value	7,731	7,916
Customer relationships [Member]
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, Cost	9,800	9,800
Finite-lived intangible assets, Accumulated amortization	(7,969)	(7,784)
Finite-lived intangible assets, Net book value	1,831	2,016
Trade name [Member]
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, Cost	5,900	5,900
Finite-lived intangible assets, Accumulated amortization	0	0
Finite-lived intangible assets, Net book value	$ 5,900	$ 5,900