Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Equity [Abstract]
Stock repurchased (in shares)				11.4
Common stock issued under stock compensation plan (in shares)				5.1
Net decrease in period (in shares)				6.3
Increase in quarterly dividend rate (in dollars per share)		$ 0.005
Dividends declared (in dollars per share)	$ 0.115		$ 0.110	$ 0.345	$ 0.330
Dividends declared	$ 29.1