Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Statement of Stockholders' Equity [Abstract]
Stock option exercises/stock unit conversions (shares)	428,599	752,075
Treasury stock, shares, acquired	601	469
Approximate cash dividends declared on preferred stock, per share	$ 0.67	$ 0.67
Cash dividends declared on common stock, per share	$ 1.24	$ 1.11