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Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 4,951	$ 4,613	$ 4,959	$ 4,083
Total realized/unrealized gains (losses):
Included in other comprehensive income		3,519		3,519
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	3,091
Sales	(106)	(136)	(114)	(2,697)
Balance at end of period	4,845	7,996	4,845	7,996
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	683	1,192	691	1,228
Total realized/unrealized gains (losses):
Included in other comprehensive income		0		0
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	0
Sales	(106)	(136)	(114)	(172)
Balance at end of period	577	1,056	577	1,056
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	4,268	3,421	4,268	2,855
Total realized/unrealized gains (losses):
Included in other comprehensive income		3,519		3,519
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	3,091
Sales	0	0	0	(2,525)
Balance at end of period	4,268	6,940	4,268	6,940
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	10,730	12,849	11,748	12,149
Total realized/unrealized gains (losses):
Included in other comprehensive income		0		0
Included in earnings and reported as losses incurred, net	(63)	651	(226)	358
Purchases	9,421	6,748	18,104	19,015
Sales	(9,817)	(10,606)	(19,355)	(21,880)
Balance at end of period	$ 10,271	$ 9,642	$ 10,271	$ 9,642

X

- Definition

Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included In Earnings, Reported As Loss Incurred, Net

+ 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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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1a)
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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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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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-Publisher FASB
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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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