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Fair Value Measurements Fair Value Measurements (Change in Fair Value of Securities Using Level 3 Inputs) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total net (losses) gains for the period included in OCI	$ 0
Total net (losses) gains for the period included in net income	0
Purchases	0
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	(5,398)
Fair value, March 31, 2018	0
Equity Securities [Member] | Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, December 31, 2017	5,398
Commercial Mortgage Backed Securities [Member] | AFS Fixed Maturity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, December 31, 2017	6,554
Total net (losses) gains for the period included in OCI	0
Total net (losses) gains for the period included in net income	0
Purchases	0
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	(6,554)
Fair value, March 31, 2018	$ 0

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+ References

No definition available.

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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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
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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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-Name Accounting Standards Codification
-Topic 820
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-Section 50
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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
-Name Accounting Standards Codification
-Topic 820
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-Section 50
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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
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-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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-Section 50
-Paragraph 2
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-Publisher FASB
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-Section 50
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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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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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