Statements of Shareholders' Equity (Parenthetical) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Issuance of common shares for stock options exercised	4,817	9,857
Preferred stock dividends per share	$ 5.00	$ 5.00
Common stock dividends per share	$ 0.16	$ 0.16
Common Stock [Member]
Issuance of common shares for stock options exercised	4,817	9,857
Additional Paid-in Capital [Member]
Issuance of common shares for stock options exercised	4,817	9,857
Retained Earnings [Member]
Preferred stock dividends per share	$ 5.00	$ 5.00
Common stock dividends per share	$ 0.16	$ 0.16