Investments (Mortgage Loans by Method of Evaluation and Related Valuation Allowances) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Mortgage Loans:
Total mortgage loans	$ 2,919,616	$ 2,718,709
Mortgage Loans on Real Estate, Commercial and Consumer, Net, (Investment Based Operations Presentation) [Abstract]
Mortgage loans on real estate (net of valuation allowances)	2,913,486	2,712,238
Commercial Real Estate Portfolio Segment
Mortgage Loans:
Evaluated individually for credit losses	16,956	17,027
Evaluated collectively for credit losses	2,902,660	2,701,682
Total mortgage loans	2,919,616	2,718,709
Valuation Allowances:
Specific for credit losses	713	816
Non-specifically identified credit losses	5,417	5,655
Total valuation allowances	$ 6,130	$ 6,471

Financing Receivable Allowance For Credit Losses Total.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount before allowance of commercial loans issued to businesses to acquire, develop, construct, improve, or refinance land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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