Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common dividends, per share amount (in usd per share)	$ 0.500	$ 0.594	$ 0.875
Special cash dividends, per share amount (in usd per share)		2.990
Series A Preferred Stock
Preferred dividends, per share amount (in usd per share)	1.375	$ 1.375	$ 1.375
Series L Preferred Stock
Preferred dividends, per share amount (in usd per share)	$ 1.738