Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common dividends declared (in dollars per share)	$ 0.49	$ 0.49	$ 0.49	$ 0.49
Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred dividends declared (in dollars per share)	0.5125	$ 0.5125	0.5125	$ 0.5125
Series B Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred dividends declared (in dollars per share)	$ 0.3667		$ 0.5156