Stock-Based Compensation (Details 2)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
$11.45 to $15.83
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	67,130
Options Outstanding, Average Remaining Life (Years)	1 year 6 months
Options Outstanding, Average Exercise Price	$ 13.43
Options Exercisable, Number of Shares | shares	67,130
Options Exercisable, Average Exercise Price	$ 13.43
Range of Exercise Prices, Lower Range Limit	11.45
Range of Exercise Prices, Upper Range Limit	$ 15.83
$20.69 to $26.32
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	77,955
Options Outstanding, Average Remaining Life (Years)	4 years 2 months 12 days
Options Outstanding, Average Exercise Price	$ 23.56
Options Exercisable, Number of Shares | shares	77,955
Options Exercisable, Average Exercise Price	$ 23.56
Range of Exercise Prices, Lower Range Limit	20.69
Range of Exercise Prices, Upper Range Limit	$ 26.32
$26.38 to $30.71
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	146,828
Options Outstanding, Average Remaining Life (Years)	7 years 6 months
Options Outstanding, Average Exercise Price	$ 30.26
Options Exercisable, Number of Shares | shares	58,173
Options Exercisable, Average Exercise Price	$ 29.58
Range of Exercise Prices, Lower Range Limit	26.38
Range of Exercise Prices, Upper Range Limit	$ 30.71
$34.92 to $37.13
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	195,005
Options Outstanding, Average Remaining Life (Years)	6 years 10 months 24 days
Options Outstanding, Average Exercise Price	$ 36.40
Options Exercisable, Number of Shares | shares	142,844
Options Exercisable, Average Exercise Price	$ 36.59
Range of Exercise Prices, Lower Range Limit	34.92
Range of Exercise Prices, Upper Range Limit	$ 37.13
$38.93 to $63.38
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	131,862
Options Outstanding, Average Remaining Life (Years)	9 years
Options Outstanding, Average Exercise Price	$ 47.28
Options Exercisable, Number of Shares | shares	5,750
Options Exercisable, Average Exercise Price	$ 38.96
Range of Exercise Prices, Lower Range Limit	38.93
Range of Exercise Prices, Upper Range Limit	$ 63.38