Consolidated Statements of Equity (Parentheticals) - $ / shares	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
$4.50 Series Preferred Stock [Member]
Preferred Stock, Dividends Per Share, Declared	$ 1.125	$ 1.125
$3.50 Series Preferred Stock [Member]
Preferred Stock, Dividends Per Share, Declared	$ 0.875	$ 0.875

Aggregate dividends declared during the period for each share of preferred stock outstanding.

No definition available.

Name:	us-gaap_PreferredStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration