Consolidating Financial Information - Schedule of Balance Sheet Information (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Assets:
Cash and cash equivalents	$ 497.3	$ 661.2	$ 728.8	$ 677.0
Funds Withheld Receivable	1,650.4	1,710.1
Receivables, net (Note 9)	556.3	613.9
Inventories, net (Note 10)	740.6	780.8
Deferred tax assets (Note 19)	798.7	548.6
Goodwill (Note 12)	2,478.4	2,487.4		1,524.8
Intangibles, net (Note 12)	2,372.5	2,480.3		2,133.1
Other assets (Note 13)	172.6	412.0
Disposal Group, Including Discontinued Operation, Assets, Current	26,738.7	24,976.5
Assets	35,792.8	35,031.5
Liabilities and Equity:
Debt	5,264.9	5,939.5
Employee benefit obligations (Note 17)	125.4	92.9
Deferred tax liabilities (Note 19)	546.0	574.5
Disposal Group, Including Discontinued Operation, Liabilities, Current	25,100.2	23,418.5
Liabilities	33,975.6	33,443.4
Stockholders' Equity Attributable to Parent	638.1	586.7
Noncontrolling interests	1,179.1	1,001.4
Total permanent equity	1,817.2	1,588.1	$ 2,257.0	$ 1,133.5
Total liabilities and equity	35,792.8	35,031.5
Consumer Products Segment
Assets:
Cash and cash equivalents	275.3	247.9
Funds Withheld Receivable	0.0	0.0
Receivables, net (Note 9)	538.2	586.6
Inventories, net (Note 10)	740.6	780.8
Deferred tax assets (Note 19)	18.3	9.3
Property, Plant and Equipment including Oil and Gas Property, Net	542.1	507.1
Goodwill (Note 12)	2,478.4	2,476.7
Intangibles, net (Note 12)	2,372.5	2,480.3
Other assets (Note 13)	103.7	105.1
Disposal Group, Including Discontinued Operation, Assets, Current	0.0	0.0
Assets	7,069.1	7,193.8
Liabilities and Equity:
Debt	3,620.2	3,905.9
Accounts payable and other current liabilities	931.6	993.0
Employee benefit obligations (Note 17)	120.2	88.1
Deferred tax liabilities (Note 19)	532.7	572.6
Other liabilities	20.4	27.3
Disposal Group, Including Discontinued Operation, Liabilities, Current	0.0	0.0
Liabilities	5,225.1	5,586.9
Stockholders' Equity Attributable to Parent	1,040.4	900.4
Noncontrolling interests	803.6	706.5
Total permanent equity	1,844.0	1,606.9
Total liabilities and equity	7,069.1	7,193.8
Insurance Segment [Member]
Assets:
Investments in subsidiaries and affiliates	3.4	10.6
Affiliated loans and receivables	20.3	31.1
Cash and cash equivalents	32.1	18.0
Funds Withheld Receivable	1,725.0	1,743.8
Receivables, net (Note 9)	17.4	25.6
Deferred tax assets (Note 19)	8.6	23.6
Other assets (Note 13)	18.1	31.1
Disposal Group, Including Discontinued Operation, Assets, Current	0.0	0.0
Assets	1,824.9	1,883.8
Liabilities and Equity:
Insurance reserves	1,685.9	1,731.9
Debt	0.0
Accounts payable and other current liabilities	6.1	5.4
Employee benefit obligations (Note 17)	0.0
Deferred tax liabilities (Note 19)	0.0
Other liabilities	3.5	7.1
Affiliated debt and payables	0.2
Disposal Group, Including Discontinued Operation, Liabilities, Current	0.0	0.0
Liabilities	1,695.7	1,744.4
Stockholders' Equity Attributable to Parent	129.2	139.4
Noncontrolling interests	0.0
Total permanent equity	129.2	139.4
Total liabilities and equity	1,824.9	1,883.8
Corporate and Other
Assets:
Investments in subsidiaries and affiliates	2,405.3	2,152.9
Affiliated loans and receivables	0.2	1.2
Cash and cash equivalents	189.9	395.3
Funds Withheld Receivable	0.0	0.0
Receivables, net (Note 9)	0.7	1.5
Deferred tax assets (Note 19)		9.6
Property, Plant and Equipment including Oil and Gas Property, Net	1.3	2.4
Goodwill (Note 12)		10.7
Other assets (Note 13)	34.6	260.3
Disposal Group, Including Discontinued Operation, Assets, Current	0.0	0.0
Assets	2,632.0	2,833.9
Liabilities and Equity:
Debt	1,747.7	1,748.0
Accounts payable and other current liabilities	51.6	61.4
Employee benefit obligations (Note 17)	5.2	4.8
Deferred tax liabilities (Note 19)	13.3	1.9
Other liabilities	8.3	13.5
Affiliated debt and payables	171.2	415.3
Disposal Group, Including Discontinued Operation, Liabilities, Current	0.0	0.0
Liabilities	1,997.3	2,244.9
Stockholders' Equity Attributable to Parent	638.1	586.7
Noncontrolling interests	(3.4)	2.3
Total permanent equity	634.7	589.0
Total liabilities and equity	2,632.0	2,833.9
Discontinued Operations, Held-for-sale [Member]
Assets:
Funds Withheld Receivable	0.0	0.0
Disposal Group, Including Discontinued Operation, Assets, Current	26,738.7	24,976.5
Assets	26,738.7	25,319.6
Liabilities and Equity:
Debt	0.0
Employee benefit obligations (Note 17)	0.0
Deferred tax liabilities (Note 19)	0.0
Other liabilities	0.0
Affiliated debt and payables	0.0
Disposal Group, Including Discontinued Operation, Liabilities, Current	25,100.2	23,418.5
Liabilities	25,100.2	23,817.1
Stockholders' Equity Attributable to Parent	1,259.6	1,209.9
Noncontrolling interests	378.9	292.6
Total permanent equity	1,638.5	1,502.5
Total liabilities and equity	26,738.7	25,319.6
Consolidation, Eliminations
Assets:
Investments in subsidiaries and affiliates	(2,408.7)	(2,163.5)
Affiliated loans and receivables	(20.5)	(32.3)
Funds Withheld Receivable	(74.6)	(33.7)
Receivables, net (Note 9)		0.2
Deferred tax assets (Note 19)	15.7	14.2
Other assets (Note 13)	16.2	15.5
Disposal Group, Including Discontinued Operation, Assets, Current	0.0	0.0
Assets	(2,471.9)	(2,199.6)
Liabilities and Equity:
Insurance reserves	65.4	124.1
Debt	63.0	330.7
Accounts payable and other current liabilities	0.5	2.2
Employee benefit obligations (Note 17)	0.0
Other liabilities	(0.2)	8.4
Affiliated debt and payables	(171.4)	(415.3)
Disposal Group, Including Discontinued Operation, Liabilities, Current	0.0	0.0
Liabilities	(42.7)	50.1
Stockholders' Equity Attributable to Parent	(2,429.2)	(2,249.7)
Noncontrolling interests	0.0
Total permanent equity	(2,429.2)	(2,249.7)
Total liabilities and equity	(2,471.9)	(2,199.6)
Consolidated Entities
Assets:
Cash and cash equivalents	497.3	661.2
Funds Withheld Receivable	1,650.4	1,710.1
Receivables, net (Note 9)	556.3	613.9
Inventories, net (Note 10)	740.6	780.8
Deferred tax assets (Note 19)	42.6	56.7
Property, Plant and Equipment including Oil and Gas Property, Net	543.4	509.5
Goodwill (Note 12)	2,478.4	2,487.4
Intangibles, net (Note 12)	2,372.5	2,480.3
Other assets (Note 13)	172.6	412.0
Disposal Group, Including Discontinued Operation, Assets, Current	26,738.7	24,976.5
Assets	35,792.8	35,031.5
Liabilities and Equity:
Insurance reserves	1,751.3	1,856.0
Debt	5,430.9	5,984.6
Accounts payable and other current liabilities	989.8	1,062.0
Employee benefit obligations (Note 17)	125.4	92.9
Deferred tax liabilities (Note 19)	546.0	574.5
Other liabilities	32.0	56.3
Disposal Group, Including Discontinued Operation, Liabilities, Current	25,100.2	23,418.5
Liabilities	33,975.6	33,443.4
Stockholders' Equity Attributable to Parent	638.1	586.7
Noncontrolling interests	1,179.1	1,001.4
Total permanent equity	1,817.2	1,588.1
Total liabilities and equity	$ 35,792.8	35,031.5
Compass Production Partners G.P. [Member]
Assets:
Cash and cash equivalents		34.0
Receivables, net (Note 9)		19.1
Property, Plant and Equipment including Oil and Gas Property, Net		288.9
Other assets (Note 13)		1.1
Compass Production Partners G.P. [Member] | Consumer Products Segment
Assets:
Disposal Group, Including Discontinued Operation, Assets, Current		0.0
Liabilities and Equity:
Disposal Group, Including Discontinued Operation, Liabilities, Current		0.0
Compass Production Partners G.P. [Member] | Insurance Segment [Member]
Assets:
Disposal Group, Including Discontinued Operation, Assets, Current		0.0
Liabilities and Equity:
Disposal Group, Including Discontinued Operation, Liabilities, Current		0.0
Compass Production Partners G.P. [Member] | Corporate and Other
Assets:
Disposal Group, Including Discontinued Operation, Assets, Current		0.0
Liabilities and Equity:
Disposal Group, Including Discontinued Operation, Liabilities, Current		0.0
Compass Production Partners G.P. [Member] | Consolidation, Eliminations
Assets:
Disposal Group, Including Discontinued Operation, Assets, Current		0.0
Liabilities and Equity:
Disposal Group, Including Discontinued Operation, Liabilities, Current		0.0
Compass Production Partners G.P. [Member] | Consolidated Entities
Assets:
Disposal Group, Including Discontinued Operation, Assets, Current		343.1
Liabilities and Equity:
Disposal Group, Including Discontinued Operation, Liabilities, Current		$ 398.6