Equity - Share-based payments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based compensation expense
Pre-tax compensation expense	$ 6	$ 4
Income tax benefit	(1)
Total share-based compensation expense, net of income taxes	5	4
Stock options
Share-based compensation expense
Pre-tax compensation expense	1	1
Total share-based compensation expense, net of income taxes	1	1
Restricted stock units (RSUs)
Share-based compensation expense
Pre-tax compensation expense	3	2
Income tax benefit	(1)
Total share-based compensation expense, net of income taxes	2	2
Performance shares and other share-based awards
Share-based compensation expense
Pre-tax compensation expense	2	1
Total share-based compensation expense, net of income taxes	$ 2	$ 1