The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

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Investments (Mortgage Loans by Method of Evaluation and Related Valuation Allowances) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Mortgage Loans:
Recorded investment	$ 5,134,898	$ 4,983,354
Valuation Allowances:
Allowance for Loan and Lease Losses, Real Estate	11,218	11,286	$ 8,864	$ 9,384
Commercial Real Estate Portfolio Segment [Member]
Mortgage Loans:
Evaluated individually for credit losses	17,079	30,635
Evaluated collectively for credit losses	5,117,819	4,952,719
Recorded investment	5,134,898	4,983,354
Valuation Allowances:
Specific for credit losses	0	0
Non-specifically identified credit losses	11,218	11,286
Allowance for Loan and Lease Losses, Real Estate	$ 11,218	$ 11,286