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Fair Value Measurement (Level 3 Assets) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation: |  |  |  |
Beginning Balance | $ 32,785 | $ 22,819 | $ 19,098 | $ 17,820
Included in earnings, as a part of: |  |  |  |
Included in other comprehensive income | (201) | 71 | (269) | (140)
Purchases | 3,225 | 4,841 | 22,683 | 11,889
Sales | (2,168) | (2,760) | (5,100) | (4,472)
Transfers in | 558 | 10 | 2,627 | 908
Transfers out | (16,357) | (3,964) | (21,115) | (4,962)
Ending Balance | 17,805 | 20,859 | 17,805 | 20,859
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end | 0 | 0 | 0 | 0
Net investment income |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | (35) | (34) | (73) | (73)
Net realized investment gains (losses) |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | (2) | (124) | (46) | (111)
Corporate Debt |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation: |  |  |  |
Beginning Balance | 15,097 | 18,914 | 13,703 | 14,810
Included in earnings, as a part of: |  |  |  |
Included in other comprehensive income | (90) | (70) | (128) | (278)
Purchases | 0 | 4,841 | 6,005 | 11,889
Sales | (1,644) | (1,848) | (4,549) | (3,560)
Transfers in | 558 | 10 | 2,627 | 10
Transfers out | (5,497) | (3,964) | (9,196) | (4,962)
Ending Balance | 8,380 | 17,849 | 8,380 | 17,849
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end | 0 | 0 | 0 | 0
Corporate Debt | Net investment income |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | (36) | (34) | (74) | (73)
Corporate Debt | Net realized investment gains (losses) |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | (8) | 0 | (8) | 13
Asset-backed Securities |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation: |  |  |  |
Beginning Balance | 17,323 | 3,002 | 4,986 | 3,007
Included in earnings, as a part of: |  |  |  |
Included in other comprehensive income | (111) | 3 | (141) | (2)
Purchases | 3,225 | 0 | 16,678 | 0
Sales | (158) | 0 | (185) | 0
Transfers in | 0 | 0 | 0 | 0
Transfers out | (10,860) | 0 | (11,919) | 0
Ending Balance | 9,420 | 3,005 | 9,420 | 3,005
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end | 0 | 0 | 0 | 0
Asset-backed Securities | Net investment income |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | 1 | 0 | 1 | 0
Asset-backed Securities | Net realized investment gains (losses) |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | 0 | 0 | 0 | 0
Other investments |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation: |  |  |  |
Beginning Balance | 365 | 903 | 409 | 3
Included in earnings, as a part of: |  |  |  |
Included in other comprehensive income | 0 | 138 | 0 | 140
Purchases | 0 | 0 | 0 | 0
Sales | (366) | (912) | (366) | (912)
Transfers in | 0 | 0 | 0 | 898
Transfers out | 0 | 0 | 0 | 0
Ending Balance | 5 | 5 | 5 | 5
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets held at period-end | 0 | 0 | 0 | 0
Other investments | Net investment income |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | 0 | 0 | 0 | 0
Other investments | Net realized investment gains (losses) |  |  |  |
Included in earnings, as a part of: |  |  |  |
Total gains (losses) realized and unrealized, included in earnings | $ 6 | $ (124) | $ (38) | $ (124)

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