Net Income Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common stockholders—basic									$ 24,370	$ 89,812	$ 651
Net income attributable to nonvested restricted stockholders									30	106	1
Net income	$ 1,112	$ 1,594	$ 20,076	$ 1,618	$ 84,239	$ 1,192	$ 5,561	$ (1,074)	$ 24,400	$ 89,918	$ 652
Weighted average common shares outstanding - basic (in shares)									16,668,745	16,502,523	16,127,610
Shares issuable under stock options (in shares)									117,007	124,879	139,524
Weighted average common shares outstanding—diluted (in shares)									16,785,752	16,627,402	16,267,134
Net income (loss) per common share - basic (in US$ per share)	$ 0.07	$ 0.10	$ 1.21	$ 0.10	$ 5.09	$ 0.07	$ 0.34	$ (0.07)	$ 1.46	$ 5.45	$ 0.04
Net income (loss) per common share - diluted (in US$ per share)	$ 0.07	$ 0.10	$ 1.20	$ 0.10	$ 5.05	$ 0.07	$ 0.34	$ (0.07)	$ 1.45	$ 5.41	$ 0.04