Fair Value of Financial Instruments - Rollforward of Balance Sheet Amounts Within Level 3 Valuation Hierarchy (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Transfers out of Level 3			$ 0
Recurring \| Other investments
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period	$ 62,129	$ 39,756	47,759	$ 38,156
Total realized gains (losses) included in income	6,957	(278)	10,397	(452)
Changes in unrealized gains/losses included in other comprehensive income	0	0	0	0
Purchases	13,124	1,366	25,556	3,727
Issuances	0	0	0	0
Settlements	(3,455)	(232)	(4,957)	(819)
Transfers out of Level 3	0	0	0	0
Fair value, end of period	78,755	40,612	78,755	40,612
Total realized gains (losses) included in income	6,957	(278)	10,397	(452)
Recurring \| Available-for-sale Securities
Assets measured on recurring basis, unobservable input reconciliation, calculation [Roll Forward]
Fair value, beginning of period	13,513	14,767	15,497	15,903
Total realized gains (losses) included in income	1,256	27	1,298	55
Changes in unrealized gains/losses included in other comprehensive income	(1,293)	501	(3,168)	480
Purchases	0	0	0	0
Issuances	0	0	0	0
Settlements	(12,636)	0	(12,787)	(1,143)
Transfers out of Level 3	0	0	0	0
Fair value, end of period	840	15,295	840	15,295
Total realized gains (losses) included in income	$ 1,256	$ 27	$ 1,298	$ 55

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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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
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- Definition

Amount of issuances 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.

+ References

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-Publisher FASB
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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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Amount of settlement 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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- Definition

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

+ References

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-Name Accounting Standards Codification
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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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