SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SUPPLEMENTARY INSURANCE INFORMATION
Net investment income	$ 79.7	$ 59.0	$ 56.0
HG Global-BAM
SUPPLEMENTARY INSURANCE INFORMATION
Deferred acquisition costs	22.1	19.0	14.8
Future policy benefits, losses, claims and loss expenses	0.0	0.0	0.0
Unearned premiums	198.4	176.0	136.8
Other policy claims and benefits payable	0.0	0.0	0.0
Premiums earned	16.3	13.9	9.4
Net investment income	21.6	16.7	12.3
Benefits, claims, losses, and settlement expenses	0.0	0.0	0.0
Amortization of deferred policy acquisition costs	5.7	5.3	4.0
Other operating expenses	0.4	0.4	0.4
Premiums written	38.7	52.9	63.2
Net investment income	21.6	16.7	12.3
Other Operations
SUPPLEMENTARY INSURANCE INFORMATION
Deferred acquisition costs	0.0	0.0	0.0
Future policy benefits, losses, claims and loss expenses	0.0	0.0	0.0
Unearned premiums	0.0	0.0	0.0
Other policy claims and benefits payable	0.0	0.0	0.0
Premiums earned	0.0	0.0	1.0
Net investment income	0.0	0.0	0.0
Benefits, claims, losses, and settlement expenses	0.0	0.0	1.1
Amortization of deferred policy acquisition costs	0.0	0.0	0.1
Other operating expenses	0.0	0.0	0.0
Premiums written	0.0	0.0	0.9
Non-insurance | Operating Segments
SUPPLEMENTARY INSURANCE INFORMATION
Net investment income	$ 43.4	$ 42.3	$ 43.7