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Comprehensive Income (Components of Comprehensive Income-Gross and Net of Tax) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Net income, Gross | $ 72,525 | $ 58,929 | $ 92,456 | $ 126,503
Unrealized holding (losses) gains during the period, Gross | (23,993) | 35,887 | (109,308) | 61,672
Non-credit portion of OTTI recognized in OCI, Gross |  | 6 |  | 6
Amounts reclassified into net income: HTM securities, Gross | (8) | (43) | (20) | (92)
Amounts reclassified into net income: Realized losses (gains) on disposals of AFS securities, Gross | 2,870 | (1,885) | 7,419 | (375)
Total unrealized (losses) gains on investment securities, Gross | (21,131) | 33,965 | (101,909) | 61,211
Amount reclassified into net income: Net actuarial loss, Gross | 531 | 508 | 1,063 | 1,015
Total defined pension and other post-retirement benefit plans, Gross | 531 | 508 | 1,063 | 1,015
Other comprehensive (loss) income, Gross | (20,600) | 34,473 | (100,846) | 62,226
Comprehensive income (loss) before tax | 51,925 | 93,402 | (8,390) | 188,729
Net income, Tax | 13,706 | 17,503 | 14,712 | 34,637
Unrealized holding (losses) gains during the period, Tax | (5,038) | 12,561 | (22,955) | 21,585
Non-credit portion of OTTI recognized in OCI, Tax |  | 2 |  | 2
Amounts reclassified into net income: HTM securities, Tax | (2) | (15) | (4) | (32)
Amounts reclassified into net income: Realized losses (gains) on disposals of AFS securities, Tax | 603 | (660) | 1,558 | (131)
Total unrealized (losses) gains on investment securities, Tax | (4,437) | 11,888 | (21,401) | 21,424
Amount reclassified into net income: Net actuarial loss, Tax | 111 | 178 | 223 | 355
Total defined pension and other post-retirement benefit plans, Tax | 111 | 178 | 223 | 355
Other comprehensive (loss) income, Tax | (4,326) | 12,066 | (21,178) | 21,779
Comprehensive income (loss), Tax | 9,380 | 29,569 | (6,466) | 56,416
Net income | 58,819 | 41,426 | 77,744 | 91,866
Unrealized holding (losses) gains arising during period | (18,955) | 23,326 | (86,353) | 40,087
Non-credit portion of OTTI recognized in OCI |  | 4 |  | 4
Amounts reclassified into net income: HTM Securities | (6) | (28) | (16) | (60)
Amounts reclassified into net income: Realized losses (gains) on disposals of available-for-sale securities | 2,267 | (1,225) | 5,861 | (244)
Total unrealized (losses) gains on investment securities | (16,694) | 22,077 | (80,508) | 39,787
Amount reclassified into net income: Net actuarial loss | 420 | 330 | 840 | 660
Total defined benefit pension and post-retirement plans | 420 | 330 | 840 | 660
Other comprehensive (loss) income | (16,274) | 22,407 | (79,668) | 40,447
Comprehensive income (loss) | $ 42,545 | $ 63,833 | $ (1,924) | $ 132,313

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