Stock-Based Compensation - Summary Stock Options Outstanding and Exercisable (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding (in shares) | shares	417,581
Options outstanding, weighted average remaining contractual life	2 years 285 days
Weighted average exercise price (in dollars per share)	$ 31.58
Options exercisable (in shares) | shares	377,292
Options exercisable, weighted average exercise price (in dollars per share)	$ 26.72
$6.22 - $6.22
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	6.22
Exercise price range, upper limit (in dollars per share)	$ 6.22
Options outstanding (in shares) | shares	139,250
Options outstanding, weighted average remaining contractual life	47 days
Weighted average exercise price (in dollars per share)	$ 6.22
Options exercisable (in shares) | shares	139,250
Options exercisable, weighted average exercise price (in dollars per share)	$ 6.22
$11.59 - $11.59
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	11.59
Exercise price range, upper limit (in dollars per share)	$ 11.59
Options outstanding (in shares) | shares	20,080
Options outstanding, weighted average remaining contractual life	1 year 47 days
Weighted average exercise price (in dollars per share)	$ 11.59
Options exercisable (in shares) | shares	20,080
Options exercisable, weighted average exercise price (in dollars per share)	$ 11.59
$12.21 - $12.21
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	12.21
Exercise price range, upper limit (in dollars per share)	$ 12.21
Options outstanding (in shares) | shares	77,400
Options outstanding, weighted average remaining contractual life	1 year 66 days
Weighted average exercise price (in dollars per share)	$ 12.21
Options exercisable (in shares) | shares	77,400
Options exercisable, weighted average exercise price (in dollars per share)	$ 12.21
$19.6 - $28.79
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	19.60
Exercise price range, upper limit (in dollars per share)	$ 28.79
Options outstanding (in shares) | shares	29,469
Options outstanding, weighted average remaining contractual life	2 years 237 days
Weighted average exercise price (in dollars per share)	$ 23.56
Options exercisable (in shares) | shares	29,469
Options exercisable, weighted average exercise price (in dollars per share)	$ 23.56
$38.4 - $38.4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	38.4
Exercise price range, upper limit (in dollars per share)	$ 38.4
Options outstanding (in shares) | shares	10,360
Options outstanding, weighted average remaining contractual life	4 years 51 days
Weighted average exercise price (in dollars per share)	$ 38.4
Options exercisable (in shares) | shares	10,360
Options exercisable, weighted average exercise price (in dollars per share)	$ 38.40
$47.5 - $47.5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	47.5
Exercise price range, upper limit (in dollars per share)	$ 47.5
Options outstanding (in shares) | shares	17,687
Options outstanding, weighted average remaining contractual life	5 years 47 days
Weighted average exercise price (in dollars per share)	$ 47.5
Options exercisable (in shares) | shares	17,687
Options exercisable, weighted average exercise price (in dollars per share)	$ 47.50
$65.36 - $65.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	65.36
Exercise price range, upper limit (in dollars per share)	$ 65.36
Options outstanding (in shares) | shares	20,395
Options outstanding, weighted average remaining contractual life	6 years 55 days
Weighted average exercise price (in dollars per share)	$ 65.36
Options exercisable (in shares) | shares	15,297
Options exercisable, weighted average exercise price (in dollars per share)	$ 65.36
$65.45 - $65.45
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	65.45
Exercise price range, upper limit (in dollars per share)	$ 65.45
Options outstanding (in shares) | shares	17,140
Options outstanding, weighted average remaining contractual life	6 years 47 days
Weighted average exercise price (in dollars per share)	$ 65.45
Options exercisable (in shares) | shares	12,345
Options exercisable, weighted average exercise price (in dollars per share)	$ 65.45
$73.52 - $73.52
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	73.52
Exercise price range, upper limit (in dollars per share)	$ 73.52
Options outstanding (in shares) | shares	50,000
Options outstanding, weighted average remaining contractual life	6 years 212 days
Weighted average exercise price (in dollars per share)	$ 73.52
Options exercisable (in shares) | shares	37,500
Options exercisable, weighted average exercise price (in dollars per share)	$ 73.52
$85.99 - $85.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit (in dollars per share)	85.99
Exercise price range, upper limit (in dollars per share)	$ 85.99
Options outstanding (in shares) | shares	35,800
Options outstanding, weighted average remaining contractual life	7 years 55 days
Weighted average exercise price (in dollars per share)	$ 85.99
Options exercisable (in shares) | shares	17,904
Options exercisable, weighted average exercise price (in dollars per share)	$ 85.99