Consolidated Statements of Changes in Stockholders' Equity Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Treasury Stock, Shares, Retired	0	1,500,000	0
Dividends on perferred stock (in dollars per share)	$ 400	$ 398	$ 424
Dividends on common stock (in dollars per share)	$ 0.59	$ 0.55	$ 0.46
Issuance of common shares pursuant to the Dividend Reinvestment Plan (in shares)	59,717	61,308	46,920
Issuance of common shares pursuant to the Deferred Compensation Plan (in shares)	6,153	13,724	12,700
Issuance of common shares pursuant to the First Retirement & Savings Plan (in shares)	11,885	8,971	9,747
Issuance of restricted common shares pursuant to the 2007 Stock Incentive Plan (in shares)	3,281	8,789	6,322
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	1,139,426	0
number of preferred shares converted to common shares	0	4,927	0
Purchase of treasury shares (in shares)	53,246	86,681	202,170
Issuance of common shares pursuant to the exercise of stock options (in shares)	0	0	39,373
Preferred Stock
Issuance of preferred stock (in shares)	0	0	0
Common Stock
Issuance of preferred stock (in shares)	1,392,859	0	0