Stock-Based Compensation Plans (Details) - Employee Stock Option [Member] $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding at beginning of year | shares	1,173,620
Shares, Granted | shares	2,500
Shares, Exercised | shares	(3,250)
Shares, Forfeited or expired | shares	(1,430)
Shares, Outstanding at end of year | shares	1,171,440
Shares, Exercisable at end of year | shares	688,757
Weighted Average Exercise Price, Outstanding at beginning of year (in dollars per share) | $ / shares	$ 27.96
Weighted Average Exercise Price, Granted (in dollars per share) | $ / shares	28.77
Weighted Average Exercise Price, Exercised (in dollars per share) | $ / shares	27.97
Weighted Average Exercise Price, Forfeited or expired (in dollars per share) | $ / shares	30.43
Weighted Average Exercise Price, Outstanding at end of year (in dollars per share) | $ / shares	27.96
Weighted Average Exercise Price, Exercisable at end of year (in dollars per share) | $ / shares	$ 26.91
Weighted Average Remaining Contractual Life (Years), Outstanding - December 31, 2018	3 years 10 months 24 days
Weighted Average Remaining Contractual Life (Years), Exercisable - December 31, 2018	2 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding at December 31, 2018 | $	$ 4,316,000	[1]
Aggregate Intrinsic Value, Exercisable at December 31, 2018 | $	$ 2,789,000	[1]

[1] The aggregate intrinsic value of outstanding and exercisable stock options is defined as the difference between the market value of the Company's stock on March 29, 2019, the last trading day of the quarter, of $30.96 and the exercise price multiplied by the number of in-the-money outstanding and exercisable stock options.