Share-Based Compensation - Stock Option Activity under Stock Option Plans (Details)	9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) | shares	59,350
Exercised (in shares) | shares	(10,050)
Ending balance (in shares) | shares	49,300
Vested and Expected to Vest (in shares) | shares	49,300
Exercisable (in shares) | shares	49,300
Weighted-Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 13.51
Exercised (in dollars per share) | $ / shares	8.29
Ending balance (in dollars per share) | $ / shares	14.57
Vested and Expected to Vest (in dollars per share) | $ / shares	14.57
Exercisable (in dollars per share) | $ / shares	$ 14.57
Weighted Average Remaining Contractual Term (in Years)
Outstanding (term)	2 years 21 days
Vested and Expected to Vest (term)	2 years 21 days
Exercisable (term)	2 years 21 days
Aggregate Intrinsic Value
Outstanding | $	$ 423,463
Vested and Expected to Vest | $	423,463
Exercisable | $	$ 423,463