Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Equity [Abstract]
Common stock issued under stock compensation plan (in shares)			2,126,386
Stock repurchased (in shares)			3,655,278
Net decrease in period (in shares)			1,528,892
Increase in quarterly cash dividend rate (in dollars per share)	$ 0.01
Dividends declared (in dollars per share)	$ 0.10	$ 0.09	$ 0.19	$ 0.175
Dividends declared	$ 28.6