Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017
Equity [Abstract]
Stock repurchased (in shares)	9.3
Stock repurchased and retired (in shares)	5.5
Stock repurchased and retired (in dollars per share)	$ 20.98
Common stock issued under stock compensation plan (in shares)	2.9
Net decrease in period (in shares)	6.4
Increase in quarterly dividend rate (in dollars per share)	$ 0.01	$ 0.01
Dividends declared (in dollars per share)	$ 0.110		$ 0.09
Dividends declared	$ 30.1