Equity - Share-based payments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based compensation expense
Pre-tax compensation expense	$ 5	$ 6
Income tax benefit		(1)
Total share-based compensation expense, net of income taxes	5	5
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	3
Income tax benefit		(1)
Total share-based compensation expense, net of income taxes	3	2
Performance shares and other share-based awards
Share-based compensation expense
Pre-tax compensation expense	1	2
Total share-based compensation expense, net of income taxes	$ 1	$ 2