Investments (Loan-To-Value and Average Debt-Service Coverage Ratios) (Details) - Mortgage Loans - Commercial Portfolio Segment - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Commercial mortgage loans, gross	$ 622,767	$ 1,153,838
Less valuation allowance	(2,582)	(2,582)
Net commercial mortgage loans	$ 620,185	$ 1,151,256
% of Gross Mortgage Loans	100.00%	100.00%
Debt-Service Coverage Ratio	1.87	1.98
70% and less
Financing Receivable, Recorded Investment [Line Items]
Commercial mortgage loans, gross	$ 592,516	$ 1,101,572
% of Gross Mortgage Loans	95.10%	95.50%
Debt-Service Coverage Ratio	1.88	2.01
71 – 80%
Financing Receivable, Recorded Investment [Line Items]
Commercial mortgage loans, gross	$ 16,585	$ 39,080
% of Gross Mortgage Loans	2.70%	3.40%
Debt-Service Coverage Ratio	1.13	1.19
81 – 95%
Financing Receivable, Recorded Investment [Line Items]
Commercial mortgage loans, gross	$ 8,850	$ 8,370
% of Gross Mortgage Loans	1.40%	0.70%
Debt-Service Coverage Ratio	1.26	1.05
Greater than 95%
Financing Receivable, Recorded Investment [Line Items]
Commercial mortgage loans, gross	$ 4,816	$ 4,816
% of Gross Mortgage Loans	0.80%	0.40%
Debt-Service Coverage Ratio	3.52	3.52

Credit Quality Percentage for Gross Commercial Mortgage Loans

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Debt-Service Coverage Ratios for Commercial Mortgage Loans

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Topic 310
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