Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ (62,758)
Debt Securities, Available-for-sale, Realized Loss			3,938	$ 0
Personnel expense	$ 124,476	$ 108,098	366,141	321,946
Change in Equity Securities(2016-01)			84
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	52	(76)	684	2,499
Total other comprehensive income (loss)	15,631	818	72,762	(391)
Ending Balance	(135,520)		(135,520)
Investment Securities Available For Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(90,986)	(19,428)	(38,453)	(20,079)
Other comprehensive income (loss) before reclassifications	(21,345)	(1,986)	(82,099)	1,646
Debt Securities, Available-for-sale, Realized Loss	(30)		1,985
Personnel expense	0	0	0	0
Other Expenses	0	0	0	0
Change in Equity Securities(2016-01)			(84)
Reporting Comprehensive Income(2018-02)			(8,419)
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	(52)	76	(684)	(2,499)
Income tax (expense) benefit	5,456	734	20,796	328
Total other comprehensive income (loss)	(15,971)	(1,176)	68,505	525
Ending Balance	(106,958)	(20,604)	(106,958)	(20,604)
Defined Benefit Pension and Post Retirement Obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(28,902)	(34,042)	(24,305)	(34,600)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Debt Securities, Available-for-sale, Realized Loss			0
Personnel expense	(37)	(38)	(112)	(113)
Other Expenses	551	621	1,480	1,596
Change in Equity Securities(2016-01)			0
Reporting Comprehensive Income(2018-02)			(5,235)
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	0	0	0	0
Income tax (expense) benefit	(174)	(225)	(390)	(567)
Total other comprehensive income (loss)	340	358	4,257	(916)
Ending Balance	(28,562)	(33,684)	(28,562)	(33,684)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(119,888)	(53,470)	(62,758)	(54,679)
Other comprehensive income (loss) before reclassifications	(21,345)	(1,986)	(82,099)	1,646
Debt Securities, Available-for-sale, Realized Loss	(30)		1,985
Personnel expense	(37)	(38)	(112)	(113)
Other Expenses	551	621	1,480	1,596
Change in Equity Securities(2016-01)			(84)
Reporting Comprehensive Income(2018-02)			(13,654)
Interest income (amortization of net unrealized losses (gains) on available for sale securities transferred to held to maturity securities)	(52)	76	(684)	(2,499)
Income tax (expense) benefit	5,282	509	20,406	(239)
Total other comprehensive income (loss)	(15,631)	(818)	72,762	(391)
Ending Balance	$ (135,520)	$ (54,288)	$ (135,520)	$ (54,288)

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Amortization of Net Unrealized Gain on Available-for-Sale Securities Transfered to Held-to-maturity Securities

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Change in Equity Securities(2016-01)

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Reporting Comprehensive Income(2018-02)

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit.

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Amount before tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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