Stockholders' Equity - Stock Options Activities (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Number
Options outstanding, Balance (in shares)	454,348
Granted (in shares)	0
Exercised (in shares)	(40,207)
Forfeited and expired (in shares)	(500)
Options outstanding, Balance (in shares)	413,641	454,348
Weighted average exercise price
Options outstanding, weighted average exercise price (in dollars per share)	$ 20.628
Granted, weighted average exercise price (in dollars per share)	0
Exercised, weighted average exercise price (in dollars per share)	20.011
Forfeited and expired, weighted average exercise price (in dollars per share)	1.576
Options outstanding, weighted average exercise price (in dollars per share)	$ 20.711	$ 20.628
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, aggregate intrinsic value	$ 17,770	$ 25,935
Options outstanding, weighted average remaining contractual life (Year)	4 years 1 month 9 days	4 years 4 months 2 days