Derivative Instruments - Schedule of Offsetting Derivative Asset and Liability Positions (Details) - Counterparty A - USD ($) $ in Thousands	Dec. 31, 2017	Jun. 30, 2017
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$ 372	$ 132
Derivative asset, netting adjustment	(372)	(132)
Derivative asset, cash collateral posted	0	0
Derivative asset, net	0	0
Derivative liability, fair value	1,923	2,369
Derivative liability, netting adjustment	(372)	(132)
Derivative liability, cash collateral posted	0	0
Derivative liability, net	$ 1,551	$ 2,237