Stock-Based Compensation Stock-Based Compensation (Activity Pertaining to Stock Options) (Details) (Stock Options, USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, beginning balance	68,920	118,030	138,980
Weighted average price, beginning balance	$ 37.81	$ 33.03	$ 31.39
Number of shares, granted	0	0	0
Weighted average price, granted	$ 0.00	$ 0.00	$ 0.00
Number of shares, exercised	(21,490)	(48,110)	(18,850)
Weighted average price, exercised	$ 37.83	$ 26.09	$ 20.38
Number of shares, forfeited	(37,930)	(1,000)	(2,100)
Weighted average price, forfeited	$ 37.83	$ 37.83	$ 37.83
Number of shares, ending balance	9,500	68,920	118,030
Weighted average price, ending balance	$ 37.69	$ 37.81	$ 33.03