Unaudited Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018
Statement of Stockholders' Equity [Abstract]
Preferred stock, dividends per share (in USD per share)	$ 1.37	$ 1.36	$ 1.37

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