Stock-Based Compensation (Details 2)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Options Outstanding and Exercisable
Number Of Options (in shares) | shares	165,920
Weighted-Average Exercise Price (in dollars per share)	$ 21.92
Weighted-Average Remaining Contractual Term	4 years 2 months 12 days
Range Of Exercise Prices From Dollars 17.18 To 17.48
Stock options outstanding
Exercise price, low end of range (in dollars per share)	$ 17.18
Exercise price, high end of range (in dollars per share)	$ 17.48
Options Outstanding and Exercisable
Number Of Options (in shares) | shares	60,267
Weighted-Average Exercise Price (in dollars per share)	$ 17.44
Weighted-Average Remaining Contractual Term	3 years 10 months 24 days
Range Of Exercise Prices From Dollars 24.18 To 24.18
Stock options outstanding
Exercise price, low end of range (in dollars per share)	$ 24.18
Exercise price, high end of range (in dollars per share)	$ 24.18
Options Outstanding and Exercisable
Number Of Options (in shares) | shares	44,151
Weighted-Average Exercise Price (in dollars per share)	$ 24.18
Weighted-Average Remaining Contractual Term	3 years 2 months 12 days
Range Of Exercise Prices From Dollars 24.68 To 24.68
Stock options outstanding
Exercise price, low end of range (in dollars per share)	$ 24.68
Exercise price, high end of range (in dollars per share)	$ 24.68
Options Outstanding and Exercisable
Number Of Options (in shares) | shares	61,502
Weighted-Average Exercise Price (in dollars per share)	$ 24.68
Weighted-Average Remaining Contractual Term	5 years 2 months 12 days