INCOME TAXES - NET OPERATING LOSSES (Details) $ in Millions	Sep. 30, 2020 USD ($)
Operating Loss Carryforwards [Line Items]
Non-life net operating loss carryforwards	$ 1,774.8
2023
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	1,188.2
2025
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	85.2
2026
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	149.9
2027
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	10.8
2028
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	80.3
2029
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	213.2
2030
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0.3
2031
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0.2
2032
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	44.4
2033
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0.6
2034
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0.9
2035
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 0.8