Stockholders' Equity (Stock Rollforward) (Details)	9 Months Ended
	Sep. 30, 2016 shares
Increase (Decrease) in Stock by Class [Roll Forward]
Common stock, beginning of period	18,931,200
Treasury stock, beginning of period	586,688
Changes related to deferred compensation plan for Boards of Directors:
Common stock, end of period	18,936,214
Treasury stock, end of period	794,857
Common Shares
Increase (Decrease) in Stock by Class [Roll Forward]
Common stock, beginning of period	18,931,200
Changes related to stock-based compensation awards:
Cancellation of restricted common shares	(10,654)
Changes related to deferred compensation plan for Boards of Directors:
Common shares issued under dividend reinvestment plan	15,668
Common stock, end of period	18,936,214
Treasury Stock
Increase (Decrease) in Stock by Class [Roll Forward]
Treasury stock, beginning of period	586,686
Changes related to stock-based compensation awards:
Release of restricted common shares	13,892
Cancellation of restricted common shares	1,000
Grant of restricted common shares	(350)
Changes related to deferred compensation plan for Boards of Directors:
Purchase of treasury stock	6,291
Reissuance of treasury stock	(12,012)
Stock Repurchased During Period, Shares	279,770
Common shares issued under compensation plan for Boards of Directors	(11,450)
Common shares issued under employee stock purchase plan	(12,970)
Treasury stock, end of period	794,857
Restricted Shares | Treasury Stock
Changes related to stock-based compensation awards:
Grant of restricted common shares	(56,000)