Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 5,846	$ 11,353	$ 5,367
Income tax benefits		1,228	2,384	1,127
Excess tax benefits (expenses) on settled share-based employee payments		$ (165)	$ (612)	$ 990
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year		45,540	50,061	40,661
Shares vested during the year		56,203	48,228	53,352
Unvested shares at end of year		71,706	93,351	91,998
Unrecognized compensation expense at end of year (in thousands)		$ 2,003	$ 2,054	$ 1,964
Total Shareholder Return Market-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year		47,848	99,214	80,724
Shares vested during the year	[1]	71,299	106,858	107,342
Shares earned based on market metrics		0	0	0
Unvested shares at end of year		122,133	178,035	187,172
Unrecognized compensation expense at end of year (in thousands)		$ 2,296	$ 3,377	$ 3,706
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year		47,848	49,609	40,329
Shares vested during the year		35,622	53,454	53,699
Shares earned based on market metrics		63,763	106,908	30,102
Unvested shares at end of year		83,464	88,990	93,579
Unrecognized compensation expense at end of year (in thousands)		$ 1,090	$ 2,401	$ 1,260

[1] The market metrics were not met during 2020, 2019 and 2018 and no TRS shares were earned during these periods.