Investments (Fixed Maturity Securities Pledged And Received As Collateral) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 17,575,507	$ 14,010,604
Available-for-sale Securities	17,708,156	14,885,583
Assets Held-in-trust	932,600	922,800
Reported Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets Held-in-trust	10,535,729	10,197,489
Reported Value Measurement [Member] \| Securities Pledged as Collateral [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	169,678	127,229
Estimate of Fair Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets Held-in-trust	10,928,393	10,922,947
Estimate of Fair Value Measurement [Member] \| Securities Pledged as Collateral [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	176,782	134,863
Estimate of Fair Value Measurement [Member] \| Collateral Received Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	$ 242,914	$ 117,227

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(b))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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No definition available.

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