Segment Data - Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			$ (185.0)	$ (301.5)
Revenues:
Consolidated revenues	$ 1,269.5	$ 1,143.8	2,503.0	2,287.5
Operating income (loss):
Consolidated operating income	115.8	(177.1)	151.1	(392.1)
Interest expense	(95.8)	(81.1)	(193.3)	(157.5)
Gain (Loss) on Disposition of Oil and Gas Property	0.0	0.0	105.6	0.0
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	0.0	0.0	0.0	141.2
Other income, net	0.5	14.1	1.6	46.9
(Loss) income from continuing operations before income taxes	20.5	(244.1)	65.0	(361.5)
Total assets:
Consolidated total assets	35,455.1		35,455.1		$ 35,034.0
Total cash provided from operating activities:
Consolidated cash provided from operating activities			(16.5)	(270.1)
Income tax expense (benefit)	8.9	(0.8)	10.8	5.2
Net income (loss)	(1.5)	(237.5)	5.5	(343.9)
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	11.6	(243.3)	54.2	(366.7)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(13.1)	5.8	(48.7)	22.8
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			(48.7)	22.8
Net Income (Loss) Attributable to Parent	(34.8)	(228.3)	(68.7)	(338.1)
Less: Net income (loss) attributable to noncontrolling interest	33.3	(9.2)	74.2	(5.8)
Total segments [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			(92.9)	(161.3)
Revenues:
Consolidated revenues	1,269.5	1,124.3	2,503.0	2,247.0
Operating income (loss):
Consolidated operating income	124.0	(152.6)	173.9	(243.8)
Intersegment elimination [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			82.5	29.9
Revenues:
Consolidated revenues	9.2	65.1	11.1	43.2
Operating income (loss):
Consolidated operating income	13.2	43.9	(5.8)	27.7
Interest expense			(2.3)	(3.2)
Gain (Loss) on Disposition of Oil and Gas Property			0.0
Gain on contingent purchase price reduction				0.0
Other income, net			(0.3)	(8.2)
(Loss) income from continuing operations before income taxes			(24.5)	239.1
Total cash provided from operating activities:
Income tax expense (benefit)			(10.7)	7.6
Net income (loss)			(13.8)	231.5
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			0.0	0.0
Net Income (Loss) Attributable to Parent			(13.8)	231.5
Other Financial Services [Member]
Operating income (loss):
Consolidated operating income	(9.2)	(67.3)
Gain on contingent purchase price reduction				0.0
Asset Management segment [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			(10.3)	(12.9)
Revenues:
Consolidated revenues	1.6	5.1	7.6	13.1
Operating income (loss):
Consolidated operating income			(18.3)	(68.5)
Gain (Loss) on Disposition of Oil and Gas Property			0.0
Other income, net			0.9	(1.5)
(Loss) income from continuing operations before income taxes			(20.8)	(84.0)
Total assets:
Consolidated total assets	201.0		201.0		334.5
Total cash provided from operating activities:
Net income (loss)			(20.8)	(84.0)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			0.0	0.0
Net Income (Loss) Attributable to Parent			(20.8)	(66.8)
Less: Net income (loss) attributable to noncontrolling interest				(17.2)
Energy Segment [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			(11.5)	7.4
Revenues:
Consolidated revenues	9.5	26.0	26.3	60.3
Operating income (loss):
Consolidated operating income	(26.7)	(161.3)	(91.2)	(356.3)
Interest expense			(3.7)	(4.4)
Gain (Loss) on Disposition of Oil and Gas Property			105.6
Gain on contingent purchase price reduction				141.2
Other income, net			2.3	24.0
(Loss) income from continuing operations before income taxes			8.5	(200.0)
Total assets:
Consolidated total assets	150.0		150.0		343.3
Total cash provided from operating activities:
Net income (loss)			8.5	(200.0)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			0.0	0.0
Net Income (Loss) Attributable to Parent			8.5	(199.5)
Less: Net income (loss) attributable to noncontrolling interest				(0.5)
Insurance Segment [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			(9.1)	(5.4)
Revenues:
Consolidated revenues	39.6	(38.9)	29.6	(4.4)
Operating income (loss):
Consolidated operating income	(1.8)	(56.3)	(1.8)	(50.7)
Gain (Loss) on Disposition of Oil and Gas Property			0.0
Gain on contingent purchase price reduction				0.0
(Loss) income from continuing operations before income taxes			(1.8)	(50.7)
Total assets:
Consolidated total assets	1,838.3		1,838.3		1,883.8
Total cash provided from operating activities:
Income tax expense (benefit)			(1.8)	(17.7)
Net income (loss)			0.0	(33.0)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			0.0	0.0
Net Income (Loss) Attributable to Parent				(33.0)
Consumer Products Segment [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			(144.5)	(180.3)
Revenues:
Consolidated revenues	1,209.6	1,067.0	2,428.4	2,134.8
Operating income (loss):
Consolidated operating income	148.5	88.4	291.0	204.0
Interest expense			(115.9)	(93.6)
Gain (Loss) on Disposition of Oil and Gas Property			0.0
Gain on contingent purchase price reduction				0.0
Other income, net			(4.3)	(3.9)
(Loss) income from continuing operations before income taxes			170.8	106.5
Total assets:
Consolidated total assets	7,263.0		7,263.0		7,193.8
Total cash provided from operating activities:
Income tax expense (benefit)			21.8	28.6
Net income (loss)			149.0	77.9
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			0.0	0.0
Net Income (Loss) Attributable to Parent			86.0	45.5
Less: Net income (loss) attributable to noncontrolling interest			63.0	32.4
Corporate expenses [Member]
Revenues:
Consolidated revenues		19.5		40.5
Operating income (loss):
Consolidated operating income	(8.2)	$ (24.5)	(22.8)	(148.3)
Interest expense			(71.4)	(56.3)
Gain (Loss) on Disposition of Oil and Gas Property			0.0
Gain on contingent purchase price reduction				0.0
Other income, net			3.0	36.5
(Loss) income from continuing operations before income taxes			(67.2)	(372.4)
Total assets:
Consolidated total assets	$ 2,559.5		2,559.5		$ 2,355.5
Total cash provided from operating activities:
Income tax expense (benefit)			1.5	(13.3)
Net income (loss)			(68.7)	(359.1)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent			0.0	0.0
Net Income (Loss) Attributable to Parent			(68.7)	(338.1)
Less: Net income (loss) attributable to noncontrolling interest				(21.0)
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Net Cash Provided by (Used in) Operating Activities, Continuing Operations			$ (92.1)	$ (140.2)