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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, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016
Net income, Gross | $ 58,929 | $ 62,311 | $ 126,503 | $ 114,186
Unrealized holding gains during the period, Gross | 35,887 | 55,675 | 61,672 | 121,412
Non Credit Portion Of Other Than Temporary Impairment Losses Recognized In Other Comprehensive Income Gross | 6 | (10) | 6 | (10)
Amounts reclassified into net income: HTM securities, Gross | (43) | (19) | (92) | (91)
Amounts reclassified into net income: Realized losses on AFS securities, Gross | (1,885) | (1,762) | (375) | 937
Total unrealized gains on investment securities, Gross | 33,965 | 53,884 | 61,211 | 122,248
Amount reclassified into net income: Net actuarial loss, Gross | 508 | 1,517 | 1,015 | 3,033
Total defined pension and other post-retirement benefit plans, Gross | 508 | 1,517 | 1,015 | 3,033
Other comprehensive income, Gross | 34,473 | 55,401 | 62,226 | 125,281
Comprehensive income before tax | 93,402 | 117,712 | 188,729 | 239,467
Net income, Tax | 17,503 | 18,710 | 34,637 | 33,553
Unrealized holding gains during the period, Tax | 12,561 | 19,487 | 21,585 | 42,495
Non-Credit Portion of Other-Than-Temporary Impairment Losses Recognized In Other Comprehensive Income, Tax | 2 | (4) | 2 | (4)
Amounts reclassified into net income: HTM securities, Tax | (15) | (7) | (32) | (32)
Amounts reclassified into net income: Realized losses on AFS securities, Tax | (660) | (617) | (131) | 328
Total unrealized gains on investment securities, Tax | 11,888 | 18,859 | 21,424 | 42,787
Amount reclassified into net income: Net actuarial loss, Tax | 178 | 532 | 355 | 1,062
Total defined pension and other post-retirement benefit plans, Tax | 178 | 532 | 355 | 1,062
Other comprehensive income, Tax | 12,066 | 19,391 | 21,779 | 43,849
Comprehensive income, Tax | 29,569 | 38,101 | 56,416 | 77,402
Net income | 41,426 | 43,601 | 91,866 | 80,633
Unrealized holding gains arising during period | 23,326 | 36,188 | 40,087 | 78,917
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Portion Attributable to Parent | 4 | 6 | 4 | 6
Amounts reclassified into net income: HTM Securities | (28) | (12) | (60) | (59)
Amounts reclassified into net income: Realized (gains) losses on available-for-sale securities | (1,225) | (1,145) | (244) | 609
Total unrealized gains on investment securities | 22,077 | 35,025 | 39,787 | 79,461
Amount reclassified into net income: Net actuarial loss | 330 | 985 | 660 | 1,971
Total defined benefit pension and post-retirement plans | 330 | 985 | 660 | 1,971
Other comprehensive income | 22,407 | 36,010 | 40,447 | 81,432
Comprehensive income | $ 63,833 | $ 79,611 | $ 132,313 | $ 162,065

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