Changes in Accumulated Other Comprehensive Income by Component - Summary of Changes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 440,780	$ 399,952	$ 338,842
Other comprehensive income (loss) before reclassifications	2,848	(844)	1,149
Losses reclassified from other comprehensive income	(87)	165	7
Net current period other comprehensive (loss) income	2,761	(679)	1,156
Ending balance	460,305	440,780	399,952
Realized loss	100	(200)	(100)
Changes in other comprehensive income (loss), tax expense (benefit)	700	(100)	300
Accumulated Other Comprehensive Income (Loss), net of Taxes
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	158	837	(319)
Ending balance	$ 2,919	$ 158	$ 837

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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