Stock Compensation - Summary of Stock Options Outstanding and Related Activity (Detail) - HGI [Member] - $ / shares shares in Thousands	9 Months Ended	12 Months Ended
	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016
Warrant [Member]
Options (in shares):
Stock options outstanding at September 30, 2016	1,200
Stock options outstanding at June 30, 2017	600	1,200
Weighted Average Exercise Price (in dollars per share):
Granted	$ 13.13	$ 13.13
Exercised	13.13
Weighted Average Grant Date Fair Value (in dollars per share):
Granted	$ 3.22	$ 3.22
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	600
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 13.13		$ 13.125
Restricted award expected to vest	$ 3.22
Employee Stock Option [Member]
Options (in shares):
Stock options outstanding at September 30, 2016	4,231
Granted	318
Exercised	(496)
Stock options outstanding at June 30, 2017	4,053	4,231
Stock options vested and exercisable at June 30, 2017	3,618
Weighted Average Exercise Price (in dollars per share):
Granted	$ 15.39
Exercised	11.12
Stock options outstanding at June 30, 2017	9.74	$ 9.48
Stock options vested and exercisable at June 30, 2017	9.15
Weighted Average Grant Date Fair Value (in dollars per share):
Granted	5.96
Exercised	4.46
Stock options outstanding at June 30, 2017	3.89	$ 3.80
Stock options vested and exercisable at June 30, 2017	$ 3.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	4,053
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 9.74
Restricted award expected to vest	$ 3.89