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Consolidated Statements of Comprehensive Income - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Statement of Comprehensive Income [Abstract] |  |  |  |
Net income | $ 37.9 | $ 41.7 | $ 79.5 | $ 78.4
Other comprehensive income (loss), before tax: |  |  |  |
Change in net unrealized gains (losses) during period | 20.2 | (3.9) | 53.8 | (27.6)
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity | 0.0 | 0.0 | (6.0) | 0.0
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity | 0.0 | 0.5 | 0.0 | 1.0
Defined benefit post-retirement benefits plans: |  |  |  |
Change in net actuarial gain | (0.2) | (0.2) | (0.3) | (0.3)
Other comprehensive income (loss), before tax | 20.0 | (3.6) | 47.5 | (26.9)
Deferred tax (expense) benefit related to other comprehensive income | (5.1) | 0.9 | (12.4) | 7.0
Other comprehensive income (loss), net of tax | 14.9 | (2.7) | 35.1 | (19.9)
Comprehensive income, net of tax | $ 52.8 | $ 39.0 | $ 114.6 | $ 58.5

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