Fair Value - Fair Value Measurements on a Recurring Basis, Unobservable Input Reconciliation (Details) - Level 3 - Available-for-sale securities - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Roll forward of level 3 fair value measurements on a recurring basis
Beginning balance	$ 10,079	$ 9,352
Included in earnings	6	(85)
Included in other comprehensive income	(302)	(41)
Purchases	6,455	7,154
Sales	(2,854)	(5,411)
Transfers into Level 3	18,232	11,196
Transfers out of Level 3	(19,039)	(12,086)
Ending balance	12,577	10,079
Change in unrealized gains or losses included in other comprehensive income related to Level 3 securities held at the reporting date
Net unrealized losses on Level 3 securities held at reporting date	(554)
Corporate debt securities
Roll forward of level 3 fair value measurements on a recurring basis
Beginning balance	7,879	9,352
Included in earnings	6	(85)
Included in other comprehensive income	(312)	(41)
Purchases	5,550	4,954
Sales	(2,854)	(5,411)
Transfers into Level 3	18,232	11,196
Transfers out of Level 3	(15,924)	(12,086)
Ending balance	12,577	7,879
Change in unrealized gains or losses included in other comprehensive income related to Level 3 securities held at the reporting date
Net unrealized losses on Level 3 securities held at reporting date	(554)
Collateralized debt obligations
Roll forward of level 3 fair value measurements on a recurring basis
Beginning balance	2,200	0
Included in earnings	0	0
Included in other comprehensive income	10	0
Purchases	905	2,200
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(3,115)	0
Ending balance	$ 0	$ 2,200

Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI [Abstract]

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Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

+ References

No definition available.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
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- Definition

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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