Earnings per share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings per share
Loss from continuing operations	$ (78)	$ (68)
Income from discontinued operations, net of tax	30	11
Net loss	$ (48)	$ (57)
Weighted average number of common shares outstanding - basic (in shares)	60.1	59.5
Weighted average number of common shares outstanding-diluted	60.1	59.5
Basic net income (loss) per common share:
Loss from continuing operations (in dollars per share)	$ (1.30)	$ (1.14)
Income from discontinued operations, net of tax (in dollars per share)	0.50	0.18
Basic loss per common share (in dollars per share)	(0.80)	(0.96)
Diluted net income (loss) per common share:
Loss from continuing operations (in dollars per share)	(1.30)	(1.14)
Income from discontinued operations, net of tax (in dollars per share)	0.50	0.18
Diluted loss per common share (in dollars per share)	$ (0.80)	$ (0.96)