Shareholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($)	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gross amounts (after reclassification adjustments)	$ 693,200,000	$ (60,900,000)	$ 695,300,000
Intangible assets adjustments	(258,200,000)	100,000	(219,600,000)
Tax effects	(225,100,000)	(47,300,000)	(189,500,000)
Noncontrolling interest	11,000,000	67,400,000	(42,600,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	220,900,000	(40,700,000)	243,600,000
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gross amounts (after reclassification adjustments)	940,500,000	147,200,000	762,200,000
Intangible assets adjustments	(258,600,000)	(300,000)	(220,000,000)
Tax effects	(237,100,000)	(51,400,000)	(190,100,000)
Noncontrolling interest	(86,000,000)	(17,400,000)	(68,500,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	358,800,000	78,100,000	283,600,000
Accumulated Other-than-Temporary Impairment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gross amounts (after reclassification adjustments)	(2,400,000)	(1,000,000.00)	(1,000,000.00)
Intangible assets adjustments	400,000	400,000	400,000
Tax effects	200,000	200,000	200,000
Noncontrolling interest	0	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,800,000)	(400,000)	(400,000)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gross amounts (after reclassification adjustments)	7,000,000	(3,000,000)	13,100,000
Intangible assets adjustments	0	0	0
Tax effects	(3,800,000)	(900,000)	(3,900,000)
Noncontrolling interest	(1,700,000)	1,300,000	(3,800,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	1,500,000	(2,600,000)	5,400,000
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gross amounts (after reclassification adjustments)	(87,700,000)	(48,400,000)	(36,200,000)
Intangible assets adjustments	0	0	0
Tax effects	12,100,000	1,300,000	800,000
Noncontrolling interest	30,400,000	18,600,000	13,600,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	(45,200,000)	(28,500,000)	(21,800,000)
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Gross amounts (after reclassification adjustments)	(164,200,000)	(155,700,000)	(42,800,000)
Intangible assets adjustments	0	0	0
Tax effects	3,500,000	3,500,000	3,500,000
Noncontrolling interest	68,300,000	64,900,000	16,100,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (92,400,000)	$ (87,300,000)	$ (23,200,000)