Income taxes - Net income (loss) before income taxes (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income (loss) before income taxes
Pre-tax (loss) income	$ (33.7)	$ 23.7	$ (109.9)
Bermuda
Net income (loss) before income taxes
Income (loss) before income taxes, Domestic	(32.8)	62.7	(95.0)
U.S.
Net income (loss) before income taxes
Income (loss) before income taxes, Foreign	(5.4)	(10.1)	(22.4)
U.K.
Net income (loss) before income taxes
Income (loss) before income taxes, Foreign	(29.1)	(14.9)	(27.0)
Sweden
Net income (loss) before income taxes
Income (loss) before income taxes, Foreign	(22.4)	(74.2)	(26.1)
Luxembourg
Net income (loss) before income taxes
Income (loss) before income taxes, Foreign	56.0	60.3	43.4
Netherlands
Net income (loss) before income taxes
Income (loss) before income taxes, Foreign	0.0	(0.1)	18.2
Other
Net income (loss) before income taxes
Income (loss) before income taxes, Foreign	$ 0.0	$ 0.0	$ (1.0)

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The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

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The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile.

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