Investment Operations Allowance on Mortgage Loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance on mortgage loans	$ 851	$ 857
Charge offs	138	6
Allowance on mortgage loans	$ 713	$ 851

Amount of direct write-downs of financing receivables charged against the allowance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration