Stock-Based Compensation Plans (Details) - Employee Stock Option [Member]	9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding at December 31, 2014	1,355,416
Shares, Granted	299,700
Shares, Exercised	(138,190)
Shares, Forfeited or expired	(14,600)
Shares, Outstanding at June 30, 2015	1,502,326
Shares, Exercisable at June 30, 2015	544,856
Weighted Average Exercise Price, Outstanding at December 31, 2014 | $ / shares	$ 25.36
Weighted Average Exercise Price, Granted | $ / shares	25.64
Weighted Average Exercise Price, Exercised | $ / shares	19.51
Weighted Average Exercise Price, Forfeited or expired | $ / shares	26.59
Weighted Average Exercise Price, Outstanding at June 30, 2015 | $ / shares	25.94
Weighted Average Exercise Price, Exercisable at June 30, 2015 | $ / shares	$ 25.20
Weighted Average Remaining Contractual Term (Years), Outstanding - June 30, 2015	3 years 10 months 24 days
Weighted Average Remaining Contractual Term (Years), Exercisable - June 30, 2015	2 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding at June 30, 2015 | $	$ 2,111,000	[1]
Aggregate Intrinsic Value, Exercisable at June 30, 2015 | $	$ 1,117,000	[1]

[1] The aggregate intrinsic value of outstanding and exercisable stock options is defined as the difference between the closing price of the Company's stock on September 30, 2015, the last trading day of the quarter, of $27.04 and the exercise price multiplied by the number of in-the-money outstanding and exercisable stock options.