Investments (Fixed Maturity and Equity Security Proceeds) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, available-for-sale			$ 854,872	$ 3,530,194
Fixed maturities \| Available-for-sale
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities	$ 115,316	$ 80,589	382,792	3,280,497
Fixed maturities, available-for-sale	156,822	100,931	480,794	295,769
Gross investment gains from sales and maturities	(1,299)	10,238	2,461	98,157
Gross investment losses from sales and maturities	(1,406)	(257)	(2,081)	(1,303)
OTTI recognized in earnings	41	(82)	(4,787)	(2,020)
Non-cash related proceeds from sales			8,700	46,100
Equity securities \| Available-for-sale
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities	0	0	0	0
Gross investment gains from sales and maturities	0	0	0	0
Gross investment losses from sales and maturities	0	0	0	0
OTTI recognized in earnings	$ 0	$ 0	$ 0	$ 0

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=82896770&loc=SL6284422-111562

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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