Consolidated Statement of Stockholders' Equity - USD ($) $ in Millions	Total	Total HC2 Stockholders' Equity	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Non- controlling Interest	Temporary Equity
Beginning balance (in shares) at Dec. 31, 2018			44,900,000
Beginning balance at Dec. 31, 2018	$ 193.7	$ 88.1	$ 0.0	$ 260.5	$ (2.6)	$ (57.2)	$ (112.6)	$ 105.6	$ 28.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	2.5	2.5		2.5
Fair value adjustment of redeemable noncontrolling interest	0.2	0.2		0.2					(0.2)
Taxes paid in lieu of shares issued for share-based compensation (in shares)			(200,000)
Taxes paid in lieu of shares issued for share-based compensation	(0.6)	(0.6)			(0.6)
Preferred stock dividend	(0.3)	(0.3)		(0.3)
Issuance of common stock (in shares)			900,000
Purchase of preferred stock by subsidiary	1.7	1.7		1.7					(10.0)
Transactions with noncontrolling interests	(3.5)	(0.5)		(0.5)			0.0	(3.0)	0.0
Other	0.3	0.3		0.3
Net income (loss)	(5.9)	(2.8)				(2.8)		(3.1)
Net loss	(6.3)								(0.4)
Other comprehensive income (loss)	149.1	148.8					148.8	0.3	1.3
Ending balance (in shares) at Mar. 31, 2019			45,600,000
Ending balance at Mar. 31, 2019	332.2	233.1	$ 0.0	264.4	(3.2)	(64.3)	36.2	99.1	17.6
Beginning balance (in shares) at Dec. 31, 2019			46,100,000
Beginning balance at Dec. 31, 2019	443.6	349.8	$ 0.0	281.1	(3.3)	(96.7)	168.7	93.8	21.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	2.6	2.6		2.6					4.1
Fair value adjustment of redeemable noncontrolling interest	$ (4.1)	(4.1)		(4.1)
Exercise of stock options (in shares)	0
Taxes paid in lieu of shares issued for share-based compensation (in shares)			(400,000)
Taxes paid in lieu of shares issued for share-based compensation	$ (0.9)	(0.9)			(0.9)
Preferred stock dividend	(0.2)	(0.2)		(0.2)
Issuance of common stock (in shares)			800,000
Transactions with noncontrolling interests	(36.8)	3.3		3.3			0.0	(40.1)	(5.5)
Net income (loss)	(98.1)	(83.1)				(83.1)		(15.0)
Net loss	(101.0)
Other comprehensive income (loss)	(245.6)	(253.3)					(253.3)	7.7
Ending balance (in shares) at Mar. 31, 2020			46,500,000
Ending balance at Mar. 31, 2020	$ 60.5	$ 14.1	$ 0.0	$ 282.7	$ (4.2)	$ (179.8)	$ (84.6)	$ 46.4	$ 18.6