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Consolidated Statements of Comprehensive Income - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Consolidated Statements of Comprehensive Income [Abstract] |  |  |
Net income | $ 161.2 | $ 181.0 | $ 160.2
Investment securities available-for-sale: |  |  |
Change in net unrealized gains (losses) during the period | 61.8 | 54.9 | (13.9)
Reclassification adjustment for net (gains) losses included in income | (0.3) | (0.1) | 0.1
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale | 0.0 | (6.0) | 0.0
Change in unamortized loss on available-for-sale investment securities transferred into held-to-maturity | 0.0 | 0.0 | 1.6
Change in net unrealized loss on derivatives | 0.2 | 0.0 | 0.0
Defined benefit post-retirement benefit plans: |  |  |
Change in net actuarial loss | (0.5) | (0.8) | (0.6)
Other comprehensive income (loss), before tax | 61.2 | 48.0 | (12.8)
Deferred tax (expense) benefit related to other comprehensive income (loss) | (15.6) | (12.4) | 3.3
Other comprehensive income (loss), net of tax | 45.6 | 35.6 | (9.5)
Comprehensive income, net of tax | $ 206.8 | $ 216.6 | $ 150.7

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