Equity - Cash Dividends (Details) - $ / shares						3 Months Ended
	Feb. 15, 2018	Oct. 27, 2017	Sep. 08, 2017	Jun. 22, 2017	Feb. 16, 2017	Mar. 31, 2018	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.96	$ 0.71	$ 0.64	$ 0.64	$ 0.64	$ 0.96	$ 0.64