Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends on common stock and dividend equivalents declared, per share	$ 1.03	$ 0.98	$ 0.89
Series A Preferred Stock [Member]
Dividends on preferred stock, per share			21.25
Series E Preferred Stock [Member]
Dividends on preferred stock, per share	$ 1,600	$ 1,600	$ 1,600