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Investments (Unrealized Gains on Investments) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Net unrealized gains | $ 124,679 | $ 64,804 | $ 69,224
Deferred income tax expense | (44,103) | (22,681) | (24,228)
Net unrealized gains, net of deferred income tax | 80,576 | 42,123 | 44,996
Increase (decrease) in net unrealized gains in OCI, net of deferred income tax | 38,453 | (2,873) | (35,398)
AFS Fixed Income Securities [Member] |  |  |
Net unrealized gains | 85,806 | 38,781 | 55,689
Equity Securities [Member] |  |  |
Net unrealized gains | 38,894 | 25,864 | 13,235
Available-for-sale Securities [Member] |  |  |
Net unrealized gains | 124,700 | 64,645 | 68,924
Total HTM Securities [Member] |  |  |
Net unrealized gains | $ (21) | $ 159 | $ 300

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- Definition Tax effect of unrealized gain (loss) on investments in accumulated other comprehensive income. + References No definition available. + Details
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- Definition This item represents the net unrealized gains (losses) on investments in other comprehensive income, net of deferred income tax. + References No definition available. + Details
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- Definition Total change in unrealized gains/losses on investment securities net of tax. + References No definition available. + Details
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- Definition This item represents the net unrealized gains (losses) on investments in other comprehensive income. + References No definition available. + Details
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