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Comprehensive Income (Components of Comprehensive Income-Gross and Net of Tax) (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2016 | Mar. 31, 2015
Net income, Gross | $ 51,875 | $ 56,290
Unrealized holding gains during the period, Gross | 65,737 | 23,977
Amounts reclassified into net income: HTM securities, Gross | (72) | (261)
Amounts reclassified into net income: Non-credit OTTI, Gross |  | 357
Realized losses (gains) on AFS securities, Gross | 2,699 | (19,895)
Net unrealized gains, Gross | 68,364 | 4,178
Amount reclassified into net income: Net actuarial loss, Gross | 1,516 | 1,709
Defined pension and other post-retirement benefit plans, Gross | 1,516 | 1,709
Other comprehensive income, Gross | 69,880 | 5,887
Comprehensive income before tax | 121,755 | 62,177
Net income, Tax | 14,843 | 16,582
Unrealized holding gains (losses) during the period, Tax | 23,008 | 8,391
Amounts reclassified into net income: HTM securities, Tax | (25) | (91)
Amounts reclassified into net income: Non-credit OTTI, Tax |  | 125
Realized losses (gains) on AFS securities, Tax | 945 | (6,963)
Net unrealized gains, Tax | 23,928 | 1,462
Amount reclassified into net income: Net actuarial loss, Tax | 530 | 598
Defined pension and other post-retirement benefit plans, Tax | 530 | 598
Other comprehensive income, Tax | 24,458 | 2,060
Comprehensive income Tax | 39,301 | 18,642
Net income | 37,032 | 39,708
Unrealized holding gains arising during period | 42,729 | 15,586
Amounts reclassified into net income: HTM Securities | (47) | (170)
Amounts reclassified into net income: Non-credit OTTI | 0 | 232
Realized losses (gains) on available-for-sale securities | 1,754 | (12,932)
Total unrealized gains on investment securities | 44,436 | 2,716
Amount reclassified into net income: Net actuarial loss | 986 | 1,111
Total defined benefit pension and post-retirement plans | 986 | 1,111
Other comprehensive income | 45,422 | 3,827
Comprehensive income | $ 82,454 | $ 43,535

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- Definition Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e640-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (e,f) -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580 + Details
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