Share-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Options, Outstanding [Roll Forward]
Stock options outstanding, ending balance (in shares)	217,875
Stock options, exercisable (in shares)	109,125
Stock Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Stock options, weighted average exercise price, beginning balance (in dollars per share)	$ 42.75	$ 37.68	$ 30.73
Stock options, granted, weighted average exercise price (in dollars per share)	46.75	42.56	53.90
Stock options, exercised, weighted average exercise price (in dollars per share)	0	15.65	14.90
Stock options, canceled, weighted average exercise price (in dollars per share)	46.66	0	0
Stock options, weighted average exercise price, ending balance (in dollars per share)	43.78	$ 42.75	$ 37.68	$ 30.73
Stock options, exercisable, weighted average exercise price (in dollars per share)	$ 40.92
Stock Options, Additional Disclosures [Abstract]
Stock options outstanding, weighted average remaining contractual term (in years)	2 years 7 months 6 days	3 years 18 days	2 years 11 months 8 days	3 years 3 months 10 days
Stock options, exercisable, weighted average remaining contractual term (in years)	1 year 4 months 28 days
Stock options outstanding, aggregate intrinsic value	$ 0	$ 0	$ 6,152	$ 2,882
Stock options, exercisable, aggregate intrinsic value	0
Proceeds from stock options exercised	0	439	52
Stock Options
Stock Options, Additional Disclosures [Abstract]
Stock options exercised in period, intrinsic value	$ 0	$ 900	$ 169
Within Plans
Stock Options, Outstanding [Roll Forward]
Stock options outstanding, beginning balance (in shares)	162,000	147,999	109,499
Granted (in shares)	66,000	42,000	42,000
Exercised (in shares)	0	(27,999)	(3,500)
Canceled (in shares)	(10,125)	0	0
Stock options outstanding, ending balance (in shares)	217,875	162,000	147,999	109,499
Stock options, exercisable (in shares)	109,125
Employee and Non-employees
Stock Options, Outstanding [Roll Forward]
Granted (in shares)	0	0	0