Share-based Payments - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of shares, outstanding at beginning of period (in shares)	624,256	764,430
Number of shares, granted (in shares)
Number of shares, expired and canceled (in shares)	(78,786)	(106,108)
Number of shares, forfeited prior to vesting (in shares)	(823)	(34,066)
Number of shares, exercised (in shares)
Number of shares, outstanding at end of period (in shares)	544,647	624,256	764,430
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, beginning of period (in dollars per share)	$ 8.87	$ 8.78
Weighted average exercise price, granted (in dollars per share)
Weighted average exercise price, expired and canceled (in dollars per share)	7.85	7.56
Weighted average exercise price, forfeited prior to vesting (in dollars per share)	11.97	10.79
Weighted average exercise price, exercised (in dollars per share)
Weighted average exercise price, end of period (in dollars per share)	$ 9.01	$ 8.87	$ 8.78
Weighted average remaining contractual term (Year)	4 years 11 months 5 days	5 years 3 months 11 days	6 years 5 months 23 days
Aggregate intrinsic value			$ 1,038
Number of shares, vested and expected to vest (in shares)	544,647	624,256
Weighted average exercise price, vested and expected to vest (in dollars per share)	$ 9.01	$ 8.87
Weighted average remaining contractual term, vested and expected to vest (Year)	4 years 11 months 5 days	5 years 3 months 11 days
Aggregate intrinsic value, vested and expected to vest
Number of shares, vested at end of period (in shares)	527,181	548,045
Weighted average exercise price, vested at end of period (in dollars per share)	$ 8.97	$ 8.62
Weighted average remaining contractual term, vested (Year)	4 years 10 months 6 days	4 years 10 months 24 days
Aggregate intrinsic value, vested

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.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.