Share-Based Payment Plans - Summary of options activity (Details) - Stock Options - $ / shares	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Options
Outstanding at beginning of year	916,425
Granted	0	0
Exercised	(65,200)
Forfeited	(1,000)
Outstanding at period end	850,225
Vested or expected to vest	850,225
Exercisable at period end	655,622
Weighted Average Exercise Price
Outstanding at beginning of year	$ 13.56
Granted	0.00
Exercised	12.50
Forfeited	24.90
Outstanding at period end	13.62
Vested or expected to vest	13.62
Exercisable at period end	$ 13.10
Weighted Average Remaining Contractual Life (Years), outstanding at period end	6 years 1 month 10 days
Weighted Average Remaining Contractual Life (Years), vested or expected to vest	6 years 1 month 10 days
Weighted Average Remaining Contractual Life (Years), exercisable at period end	5 years 11 months 5 days

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.