Quarterly report pursuant to Section 13 or 15(d)

Available-for-Sale Securities, at Fair Value Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details)

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Available-for-Sale Securities, at Fair Value Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
position
Sep. 30, 2016
USD ($)
position
Available-for-sale Securities [Abstract]        
Other-than-temporary impairment losses $ 0 $ (1,015) $ (429) $ (1,822)
Other than Temporary Impairment Losses, Investments, Number, Available-for-sale Securities | position     1 4
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Market Value $ 117,620   $ 117,620  
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Weighted Average Cumulative Losses 5.30%      
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Weighted Average Three-Month Prepayment Speed 0.073      
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Delinquency Rate 21.80%      
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Weighted Average FICO Score 659      
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]        
Cumulative credit loss at beginning of period $ (6,035) (6,710) (5,606) $ (6,499)
Other-than-temporary impairments not previously recognized 0 (1,015) (429) (1,307)
Increases related to other-than-temporary impairments on securities with previously recognized other-than-temporary impairments 0 0 0 (515)
Decreases related to other-than-temporary impairments on securities paid down 0 0 0 0
Decreases related to other-than-temporary impairments on securities sold 0 0 0 596
Cumulative credit loss at end of period $ (6,035) $ (7,725) $ (6,035) $ (7,725)