Stock Options (Schedule of Non-Qualified Stock Options Outstanding and Exercisable) (Details) - Non Qualified Options - $ / shares		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Shares, Total		127,300	132,100	114,700	89,700
Options Exercisable, Shares, Total		83,100	71,100	57,900
$11.45 - $22.39
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Range Limit		$ 11.45
Range of Exercise Price, Upper Range Limit		$ 22.39
Options Outstanding, Shares		30,800
Options Outstanding, Remaining Contractual Life	[1]	3 years 4 months 10 days
Options Outstanding, Exercise Price	[1]	$ 11.45
Options Exercisable, Shares		30,800
Options Exercisable, Exercise Price	[1]	$ 11.45
$22.55 - $42.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Range Limit		22.55
Range of Exercise Price, Upper Range Limit		$ 42.70
Options Outstanding, Shares		67,500
Options Outstanding, Remaining Contractual Life	[1]	5 years 3 months 29 days
Options Outstanding, Exercise Price	[1]	$ 32.23
Options Exercisable, Shares		46,500
Options Exercisable, Exercise Price	[1]	$ 29.59
$49.44 - $54.24
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Range Limit		49.44
Range of Exercise Price, Upper Range Limit		$ 54.24
Options Outstanding, Shares		29,000
Options Outstanding, Remaining Contractual Life	[1]	8 years 4 months 13 days
Options Outstanding, Exercise Price	[1]	$ 53.51
Options Exercisable, Shares		5,800
Options Exercisable, Exercise Price	[1]	$ 53.51

[1] Weighted Averages