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Comprehensive Income (Components of Comprehensive Income-Gross and Net of Tax) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015
Net income, Gross | $ 55,443 | $ 65,839 | $ 169,629 | $ 168,894
Unrealized holding (losses) gains during the period, Gross | (12,992) | 8,371 | 108,420 | (27,896)
Non-credit portion of OTTI recognized in OCI, Gross |  |  | (10) |
Amounts reclassified into net income: HTM securities, Gross | (13) | (97) | (104) | (543)
Amounts reclassified into net income: Non-credit OTTI, Gross |  |  |  | 357
Realized gains on AFS securities, Gross | (3,684) | (305) | (2,747) | (16,778)
Total unrealized (losses) gains on investment securities, Gross | (16,689) | 7,969 | 105,559 | (44,860)
Amount reclassified into net income: Net actuarial loss, Gross | 1,615 | 1,709 | 4,648 | 5,127
Total defined pension and other post-retirement benefit plans, Gross | 1,615 | 1,709 | 4,648 | 5,127
Other comprehensive (loss) income, Gross | (15,074) | 9,678 | 110,207 | (39,733)
Comprehensive income before tax | 40,369 | 75,517 | 279,836 | 129,161
Net income, Tax | 16,941 | 18,843 | 50,494 | 48,422
Unrealized holding (losses) gains during the period, Tax | (4,548) | 2,929 | 37,947 | (9,764)
Non-credit portion of OTTI recognized in OCI, Tax |  |  | (4) |
Amounts reclassified into net income: HTM securities, Tax | (4) | (34) | (36) | (190)
Amounts reclassified into net income: Non-credit OTTI, Tax |  |  |  | 125
Realized gains on AFS securities, Tax | (1,289) | (106) | (961) | (5,872)
Total unrealized (losses) gains on investment securities, Tax | (5,841) | 2,789 | 36,946 | (15,701)
Amount reclassified into net income: Net actuarial loss, Tax | 565 | 599 | 1,627 | 1,795
Total defined pension and other post-retirement benefit plans, Tax | 565 | 599 | 1,627 | 1,795
Other comprehensive (loss) income, Tax | (5,276) | 3,388 | 38,573 | (13,906)
Comprehensive income, Tax | 11,665 | 22,231 | 89,067 | 34,516
Net income | 38,502 | 46,996 | 119,135 | 120,472
Unrealized holding (losses) gains arising during period | (8,444) | 5,442 | 70,473 | (18,132)
Non-credit portion of OTTI recognized in OCI |  |  | (6) |
Amounts reclassified into net income: HTM Securities | (9) | (63) | (68) | (353)
Amounts reclassified into net income: Non-credit OTTI | 0 | 0 | 0 | 232
Realized gains on available-for-sale securities | (2,395) | (199) | (1,786) | (10,906)
Total unrealized (losses) gains on investment securities | (10,848) | 5,180 | 68,613 | (29,159)
Amount reclassified into net income: Net actuarial loss | 1,050 | 1,110 | 3,021 | 3,332
Total defined benefit pension and post-retirement plans | 1,050 | 1,110 | 3,021 | 3,332
Other comprehensive (loss) income | (9,798) | 6,290 | 71,634 | (25,827)
Comprehensive income | $ 28,704 | $ 53,286 | $ 190,769 | $ 94,645

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