Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - $ / shares			3 Months Ended		6 Months Ended
	May 15, 2018	May 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in $ per share)	$ 0.45		$ 0.45	$ 0.45	$ 0.90	$ 0.90
Cash dividends declared per preferred share (in $ per share)		$ 1.8125	$ 1.81	$ 1.81	$ 3.63	$ 3.63