Stock-based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date			Mar. 31, 2018
Stock-based compensation	$ (3.1)	$ (14.0)	$ (1.1)	$ (23.5)
HGI
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity intruments other than options granted			24
Granted			$ 400,000
Exercised / Released			$ 4,900,000	$ 29,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value			$ 18.2	$ 2.8
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options			10.1	$ 5.5
Compensation cost not yet recognized	0.7		$ 0.7
Unrecognized compensation cost expected to recognized, years			1 year 1 month 10 days
HGI | Stock option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual term of outstanding stock option awards			3 years 8 months 13 days
HGI | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, granted			0
Granted			$ 0.00
Exercised / Released			$ 0
HGI | Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			143
Exercised / Released			$ 13.36
HGI | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value			$ 0
Equity intruments other than options granted			0
Granted			$ 0.00
Exercised / Released			$ 0.00
Stock Issued During Period, Shares, Restricted Stock Award, Gross			0
HGI | Time Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity intruments other than options granted			24
Granted			$ 16.85
Exercised / Released			400,000
HGI | Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			3.22
Granted			13.13
Spectrum Brands [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			10,500,000
Exercised / Released			$ 25,200,000
Stock Issued During Period, Shares, Restricted Stock Award, Gross			93
Spectrum Brands [Member] | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, granted			0
Granted			$ 0.00
Exercised / Released			0
Spectrum Brands [Member] | Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			$ 113.28
Spectrum Brands [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			464
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value			$ 10,500,000
Equity intruments other than options granted			323
Granted			$ 110.55
Exercised / Released			$ 113.25
Compensation cost not yet recognized	$ 3.5		$ 3.5
Stock Issued During Period, Shares, Restricted Stock Award, Gross			93
Equity instruments other than options, grant date fair value			$ 69.5
Spectrum Brands [Member] | Time Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity intruments other than options granted			0
Granted			$ 0.00
Exercised / Released			0
Spectrum Brands [Member] | Performance-based and Time-based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			$ 109.45
Stock Issued During Period, Shares, Restricted Stock Award, Gross			230
Share-based Compensation Award, Tranche Two [Member] | Spectrum Brands [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercised / Released			$ 12,600,000
Share-based Compensation Award, Tranche Two [Member] | Spectrum Brands [Member] | Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			$ 109.45
Share-based Compensation Award, Tranche Two [Member] | Spectrum Brands [Member] | Performance-based and Time-based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Gross			115