Consolidating Financial Information - Schedule of Balance Sheet Information (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012	Jan. 01, 2012	Sep. 30, 2011
Assets:
Investments	$ 16,600.5	$ 16,918.4
Cash and cash equivalents	1,243.7	1,470.7	1,832.8	1,137.4
Receivables, net	611.3	414.4
Inventories, net	707.3	452.6
Accrued investment income	159.9	191.6
Reinsurance recoverable	2,371.0	2,363.1
Deferred tax assets	279.9	312.7
Properties, including oil and natural gas properties, net	999.4	221.6
Goodwill	1,470.2	694.2
Intangibles, including DAC and VOBA, net	2,649.9	1,988.5
Other assets	271.9	172.6
Total assets	27,365.0	25,200.4
Liabilities and Equity:
Debt	4,513.5	2,150.6
Accounts payable and other current liabilities	430.6	325.9
Equity conversion feature of preferred stock	147.3	232.0
Employee benefit obligations	114.1	95.1
Deferred tax liabilities	508.4	382.4
Other liabilities	439.6	600.6
Total liabilities	25,632.3	23,282.3
Temporary equity	325.4	319.2
Total stockholders' equity	985.4	1,177.6
Noncontrolling interests	421.9	421.3
Total permanent equity	1,407.3	1,598.9
Total liabilities and equity	27,365.0	25,200.4
Consumer Products [Member]
Assets:
Investments
Investments in subsidiaries and affiliates
Affiliated loans and receivables
Cash and cash equivalents	99.0	158.0
Receivables, net	542.1	373.4
Inventories, net	707.3	452.6
Accrued investment income
Reinsurance recoverable
Deferred tax assets	21.3	28.2
Properties, including oil and natural gas properties, net	355.2	214.0
Goodwill	1,470.2	694.2
Intangibles, including DAC and VOBA, net	2,169.4	1,715.0
Other assets	173.0	116.2
Total assets	5,537.5	3,751.6
Liabilities and Equity:
Insurance reserves
Debt	3,226.1	1,669.3
Accounts payable and other current liabilities	704.3	594.2
Equity conversion feature of preferred stock
Employee benefit obligations	109.3	90.0
Deferred tax liabilities	503.5	377.5
Other liabilities	24.8	31.6
Affiliated debt and payables
Total liabilities	4,568.0	2,762.6
Temporary equity
Total stockholders' equity	547.2	567.7
Noncontrolling interests	422.3	421.3
Total permanent equity	969.5	989.0
Total liabilities and equity	5,537.5	3,751.6
Insurance [Member]
Assets:
Investments	16,298.5	16,556.7
Investments in subsidiaries and affiliates	62.0	32.0
Affiliated loans and receivables	277.2	150.1
Cash and cash equivalents	1,003.0	1,054.6
Receivables, net	41.0	41.0
Inventories, net
Accrued investment income	158.1	191.6
Reinsurance recoverable	2,371.0	2,363.1
Deferred tax assets	253.7	279.6
Properties, including oil and natural gas properties, net	7.0	6.9
Goodwill
Intangibles, including DAC and VOBA, net	480.5	273.5
Other assets	60.6	41.2
Total assets	21,012.6	20,990.3
Liabilities and Equity:
Insurance reserves	19,025.2	19,051.0
Debt	300.0
Accounts payable and other current liabilities	27.4	93.2
Equity conversion feature of preferred stock
Employee benefit obligations
Deferred tax liabilities
Other liabilities	373.1	555.3
Affiliated debt and payables	1.2
Total liabilities	19,726.9	19,699.5
Temporary equity
Total stockholders' equity	1,285.7	1,290.8
Noncontrolling interests
Total permanent equity	1,285.7	1,290.8
Total liabilities and equity	21,012.6	20,990.3
Energy Segment [Member]
Assets:
Investments
Investments in subsidiaries and affiliates
Affiliated loans and receivables
Cash and cash equivalents	16.5
Receivables, net	27.7
Inventories, net
Accrued investment income
Reinsurance recoverable
Deferred tax assets
Properties, including oil and natural gas properties, net	636.0
Goodwill
Intangibles, including DAC and VOBA, net
Other assets	5.3
Total assets	685.5
Liabilities and Equity:
Insurance reserves
Debt	274.9
Accounts payable and other current liabilities	31.6
Equity conversion feature of preferred stock
Employee benefit obligations
Deferred tax liabilities
Other liabilities	25.7
Affiliated debt and payables	103.4
Total liabilities	435.6
Temporary equity
Total stockholders' equity	249.9
Noncontrolling interests
Total permanent equity	249.9
Total liabilities and equity	685.5
Other Financial Services [Member]
Assets:
Investments	268.0	180.1
Investments in subsidiaries and affiliates
Affiliated loans and receivables	1.2
Cash and cash equivalents	37.2	12.4
Receivables, net	0.5
Inventories, net
Accrued investment income	1.8
Reinsurance recoverable
Deferred tax assets
Properties, including oil and natural gas properties, net	0.6	0.4
Goodwill
Intangibles, including DAC and VOBA, net
Other assets	7.6	2.2
Total assets	316.9	195.1
Liabilities and Equity:
Insurance reserves
Debt	57.5
Accounts payable and other current liabilities	3.3
Equity conversion feature of preferred stock
Employee benefit obligations
Deferred tax liabilities
Other liabilities	14.9	13.3
Affiliated debt and payables	173.8	150.1
Total liabilities	249.5	163.4
Temporary equity
Total stockholders' equity	67.8	31.7
Noncontrolling interests	(0.4)
Total permanent equity	67.4	31.7
Total liabilities and equity	316.9	195.1
Corporate and Other [Member]
Assets:
Investments	34.0	181.6
Investments in subsidiaries and affiliates	2,088.6	1,858.2
Affiliated loans and receivables
Cash and cash equivalents	88.0	245.7
Receivables, net
Inventories, net
Accrued investment income
Reinsurance recoverable
Deferred tax assets	4.9	4.9
Properties, including oil and natural gas properties, net	0.6	0.3
Goodwill
Intangibles, including DAC and VOBA, net
Other assets	25.4	13.0
Total assets	2,241.5	2,303.7
Liabilities and Equity:
Insurance reserves
Debt	695.8	497.7
Accounts payable and other current liabilities	76.8	66.8
Equity conversion feature of preferred stock	147.3	232.0
Employee benefit obligations	4.8	5.1
Deferred tax liabilities	4.9	4.9
Other liabilities	1.1	0.4
Affiliated debt and payables
Total liabilities	930.7	806.9
Temporary equity	325.4	319.2
Total stockholders' equity	985.4	1,177.6
Noncontrolling interests
Total permanent equity	985.4	1,177.6
Total liabilities and equity	2,241.5	2,303.7
Consolidation, Eliminations [Member]
Assets:
Investments
Investments in subsidiaries and affiliates	(2,150.6)	(1,890.2)
Affiliated loans and receivables	(278.4)	(150.1)
Cash and cash equivalents
Receivables, net
Inventories, net
Accrued investment income
Reinsurance recoverable
Deferred tax assets
Properties, including oil and natural gas properties, net
Goodwill
Intangibles, including DAC and VOBA, net
Other assets
Total assets	(2,429.0)	(2,040.3)
Liabilities and Equity:
Insurance reserves
Debt
Accounts payable and other current liabilities
Equity conversion feature of preferred stock
Employee benefit obligations
Deferred tax liabilities
Other liabilities
Affiliated debt and payables	(278.4)	(150.1)
Total liabilities	(278.4)	(150.1)
Temporary equity
Total stockholders' equity	(2,150.6)	(1,890.2)
Noncontrolling interests
Total permanent equity	(2,150.6)	(1,890.2)
Total liabilities and equity	(2,429.0)	(2,040.3)
Consolidated Entities [Member]
Assets:
Investments	16,600.5	16,918.4
Investments in subsidiaries and affiliates
Affiliated loans and receivables
Cash and cash equivalents	1,243.7	1,470.7
Receivables, net	611.3	414.4
Inventories, net	707.3	452.6
Accrued investment income	159.9	191.6
Reinsurance recoverable	2,371.0	2,363.1
Deferred tax assets	279.9	312.7
Properties, including oil and natural gas properties, net	999.4	221.6
Goodwill	1,470.2	694.2
Intangibles, including DAC and VOBA, net	2,649.9	1,988.5
Other assets	271.9	172.6
Total assets	27,365.0	25,200.4
Liabilities and Equity:
Insurance reserves	19,025.2	19,051.0
Debt	4,554.3	2,167.0
Accounts payable and other current liabilities	843.4	754.2
Equity conversion feature of preferred stock	147.3	232.0
Employee benefit obligations	114.1	95.1
Deferred tax liabilities	508.4	382.4
Other liabilities	439.6	600.6
Affiliated debt and payables
Total liabilities	25,632.3	23,282.3
Temporary equity	325.4	319.2
Total stockholders' equity	985.4	1,177.6
Noncontrolling interests	421.9	421.3
Total permanent equity	1,407.3	1,598.9
Total liabilities and equity	$ 27,365.0	$ 25,200.4