Changes in Accumulated Other Comprehensive Income by Component - Summary of Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Accumulated other comprehensive income
Beginning balance	$ 338,842
Other comprehensive income before reclassifications	963	$ 1,286
Losses (gains) reclassified from other comprehensive income	118	(153)
Net current period change in other comprehensive income	1,081	1,133
Ending balance	376,077
Available-for-sale securities, tax	600	600
Accumulated Other Comprehensive Income (Loss), net of taxes
Accumulated other comprehensive income
Beginning balance	(319)	543
Ending balance	$ 762	$ 1,676

Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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