Earnings Per Share - Summary of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	$ (0.08)	$ 0.04	$ (0.30)	$ 0.11
Net Income (Loss) Available to Common Stockholders, Basic	$ (34.8)	$ (228.3)
Weighted Average Number of Shares Outstanding, Diluted	198,521	196,860	198,076	197,583
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			$ (48.7)	$ 22.8
Net income (loss) attributable to common and participating preferred stockholders	$ (34.8)	$ (228.3)	(68.7)	(338.1)
Net Income (Loss) Attributable to Parent	(34.8)	(228.3)	(68.7)	(338.1)
Income (Loss) from Continuing Operations Attributable to Parent	$ (19.9)	$ (236.9)	$ (8.8)	$ (360.4)
Dilutive adjustments to income (loss) attributable to common shares from assumed conversion of preferred shares, net of tax:
Weighted-average common shares outstanding - basic	198,521	196,860	198,076	197,583
Net loss per common share attributable to controlling interest:
Basic (in dollars per share)	$ (0.18)	$ (1.16)	$ (0.35)	$ (1.71)
Income (Loss) from Continuing Operations, Per Diluted Share	(0.10)	(1.20)	(0.05)	(1.82)
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	(0.08)	0.04	(0.30)	0.11
Earnings Per Share, Diluted	(0.18)	(1.16)	(0.35)	(1.71)
Income (Loss) from Continuing Operations, Per Basic Share	$ (0.10)	$ (1.20)	$ (0.05)	$ (1.82)
Stock option awards [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,040	1,316	1,172	1,393
Restricted stock awards [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,501	3,092	2,130	2,861
HGI [Member] | Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price			$ 13.13		$ 13.13