Funds Withheld Receivables (Details) $ in Millions	3 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Document Fiscal Year Focus	2017
Document Period End Date	Dec. 31, 2016
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	$ 24.9
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	24.9
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	265.2
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	261.1
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	428.9
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	423.8
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	497.1
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	477.0
Available For Sale Securities Debt Maturities Amortized Cost Excluding Single Maturity Date	1,216.1
Available For Sale Securities Debt Maturities Fair Value Excluding Single Maturity Date	1,186.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	255.7		$ 216.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8.7		15.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	287.8		190.7
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	32.4		22.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	543.5		406.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	41.1		$ 38.3
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	1.0	$ 1.4
Gross Investment Income	10.7	20.3
Gain (Loss) on Sale of Equity Investments	(0.1)	1.8
Gain (Loss) on Sale of Derivatives	3.1	1.9
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net	(12.2)	(26.5)
Gain (Loss) on Sale of Other Investments	(22.4)	(12.5)
Net investment losses	$ (33.8)	(32.0)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	198		146
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	137		76
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	335		222
Fixed Maturity Available For Sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Investment Income	$ 10.2	15.5
Gain Loss On Sale Of Available For Sale Securities	(2.2)	3.3
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	202.7		$ 137.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	7.9		12.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	162.4		91.7
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	24.9		16.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	365.1		229.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	32.8		29.5
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	1.0	1.4
Mortgage Backed Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	331.8
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	324.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	44.3		73.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.2		2.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	120.2		99.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	7.1		5.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	164.5		172.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	7.3		7.9
Municipal Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	6.8		1.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.4		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0.0		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6.8		1.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0.4		0.0
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1.0		0.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.1		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0.0		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1.0		0.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0.1		0.0
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0.9		3.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.1		0.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5.2		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.4		0.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6.1		3.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0.5		0.9
Structured Hybrids [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	22.2
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	21.1
Equity Securities Available For Sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Investment Income	0.2	0.6
Asset based loan receivables [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Investment Income	0.3	2.0
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Investment Income	0.0	$ 2.2
Funds Withheld Receivables [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,643.4		1,645.6
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	21.8		47.7
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(56.2)		(42.9)
Available-for-sale Securities, Debt Securities	1,609.0		1,650.4
Total investments, Carrying Value	1,609.0		1,650.4
Policy Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	8.3		8.5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		0.0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0.0		0.0
Available-for-sale Securities, Debt Securities	8.3		8.5
Total investments, Carrying Value	8.3		8.5
Receivables, net [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	39.1		77.7
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		0.0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0.0		0.0
Available-for-sale Securities, Debt Securities	39.1		77.7
Total investments, Carrying Value	39.1		77.7
Accrued Income Receivable [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	16.6		17.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		0.0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0.0		0.0
Available-for-sale Securities, Debt Securities	16.6		17.8
Total investments, Carrying Value	16.6		17.8
Fixed Maturities Available For Sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,570.1		1,531.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	18.9		46.2
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(56.2)		(42.9)
Available-for-sale Securities, Debt Securities	1,532.8		1,535.1
Total investments, Carrying Value	1,532.8		1,535.1
Third party cedants [Member] | Fixed Maturities Available For Sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	670.0		632.5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	8.6		26.4
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(15.1)		(4.6)
Available-for-sale Securities, Debt Securities	663.5		654.3
Total investments, Carrying Value	663.5		654.3
Third party cedants [Member] | Fixed Maturities Available For Sale [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	397.5		390.0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	5.9		18.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(8.8)		(2.7)
Available-for-sale Securities, Debt Securities	394.6		406.1
Total investments, Carrying Value	394.6		406.1
Third party cedants [Member] | Fixed Maturities Available For Sale [Member] | Mortgage Backed Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	133.9		118.7
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1.7		1.9
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(1.8)		(1.7)
Available-for-sale Securities, Debt Securities	133.8		118.9
Total investments, Carrying Value	133.8		118.9
Third party cedants [Member] | Fixed Maturities Available For Sale [Member] | Municipal Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	49.4		49.5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1.0		4.1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.6)		0.0
Available-for-sale Securities, Debt Securities	49.8		53.6
Total investments, Carrying Value	49.8		53.6
Third party cedants [Member] | Fixed Maturities Available For Sale [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	82.5		67.7
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		1.3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(3.9)		(0.2)
Available-for-sale Securities, Debt Securities	78.6		68.8
Total investments, Carrying Value	78.6		68.8
Third party cedants [Member] | Fixed Maturities Available For Sale [Member] | Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	6.7		6.6
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		0.3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0.0		0.0
Available-for-sale Securities, Debt Securities	6.7		6.9
Total investments, Carrying Value	6.7		6.9
FGL [Member] | Derivative Financial Instruments, Assets [Member] | Call options [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	9.3		9.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2.9		1.5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0.0		0.0
Available-for-sale Securities, Debt Securities	12.2		11.3
Total investments, Carrying Value	12.2		11.3
FGL [Member] | Fixed Maturities Available For Sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	900.1		899.3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	10.3		19.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(41.1)		(38.3)
Available-for-sale Securities, Debt Securities	869.3		880.8
Total investments, Carrying Value	869.3		880.8
FGL [Member] | Fixed Maturities Available For Sale [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	676.5		638.5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	9.7		18.2
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(32.8)		(29.5)
Available-for-sale Securities, Debt Securities	653.4		627.2
Total investments, Carrying Value	653.4		627.2
FGL [Member] | Fixed Maturities Available For Sale [Member] | Mortgage Backed Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	197.9		238.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.5		0.6
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(7.3)		(7.9)
Available-for-sale Securities, Debt Securities	191.1		231.5
Total investments, Carrying Value	191.1		231.5
FGL [Member] | Fixed Maturities Available For Sale [Member] | Municipal Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	12.1		12.1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		0.7
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.4)		0.0
Available-for-sale Securities, Debt Securities	11.7		12.8
Total investments, Carrying Value	11.7		12.8
FGL [Member] | Fixed Maturities Available For Sale [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1.1		1.1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.0		0.0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.1)		0.0
Available-for-sale Securities, Debt Securities	1.0		1.1
Total investments, Carrying Value	1.0		1.1
FGL [Member] | Fixed Maturities Available For Sale [Member] | Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	12.5		8.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0.1		0.3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.5)		(0.9)
Available-for-sale Securities, Debt Securities	12.1		8.2
Total investments, Carrying Value	$ 12.1		$ 8.2
HGI [Member]
Schedule of Available-for-sale Securities [Line Items]
Document Fiscal Year Focus	2016