Equity - Cash Dividends on Shares of Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		6 Months Ended
	Apr. 25, 2017	Jan. 26, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stockholders' Equity Note [Abstract]
Cash dividends declared per common stock (in dollars per share)	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.20	$ 0.20
Common stock dividends paid					$ 75.8