SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SUPPLEMENTARY INSURANCE INFORMATION
Net investment income	$ 59.0	$ 56.0	$ 32.1
HG Global-BAM
SUPPLEMENTARY INSURANCE INFORMATION
Deferred acquisition costs	19.0	14.8	10.6
Future policy benefits, losses, claims and loss expenses	0.0	0.0	0.0
Unearned premiums	176.0	136.8	82.9
Other policy claims and benefits payable	0.0	0.0	0.0
Premiums earned	13.9	9.4	5.9
Net investment income	16.7	12.3	9.0
Benefits, claims, losses, and settlement expenses	0.0	0.0	0.0
Amortization of deferred policy acquisition costs	5.3	4.0	3.4
Other operating expenses	0.4	0.4	0.4
Premiums written	52.9	63.2	38.6
Net investment income	16.7	12.3	9.0
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	1.0	7.5
Net investment income	0.0	0.0	0.2
Benefits, claims, losses, and settlement expenses	0.0	1.1	8.0
Amortization of deferred policy acquisition costs	0.0	0.1	2.2
Other operating expenses	0.0	0.0	0.1
Premiums written	0.0	0.9	6.5
Non-insurance [Member] | Operating Segments
SUPPLEMENTARY INSURANCE INFORMATION
Net investment income	$ 0.0	$ 43.7	$ 22.9