Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ (54,679)
Personnel expense	$ (104,683)	$ (102,129)	(209,102)	$ (203,527)
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	(1,548)	(1,452)	(2,575)	(3,024)
Total other comprehensive income	2,874	11,286	1,209	46,069
Ending Balance	(53,470)		(53,470)
Investments Securities Available For Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(22,023)	34,936	(20,079)	459
Other comprehensive income (loss) before reclassifications	5,744	22,321	3,632	82,743
Investment securities gain, net		(3,116)		(6,214)
Personnel expense	0	0	0	0
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	(1,548)	(1,452)	(2,575)	(3,024)
Income tax (expense) benefit	(1,601)	(6,773)	(406)	(28,048)
Total other comprehensive income	2,595	10,980	651	45,457
Ending Balance	(19,428)	45,916	(19,428)	45,916
Defined Benefit Pension and Post Retirement Obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(34,321)	(32,769)	(34,600)	(33,075)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Investment securities gain, net		0		0
Personnel expense	450	495	900	990
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	0	0	0	0
Income tax (expense) benefit	(171)	(189)	(342)	(378)
Total other comprehensive income	279	306	558	612
Ending Balance	(34,042)	(32,463)	(34,042)	(32,463)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(56,344)	2,167	(54,679)	(32,616)
Other comprehensive income (loss) before reclassifications	5,744	22,321	3,632	82,743
Investment securities gain, net		(3,116)		(6,214)
Personnel expense	450	495	900	990
Interest income (Amortization of net unrealized gains on available for sale securities transferred to held to maturity securities)	(1,548)	(1,452)	(2,575)	(3,024)
Income tax (expense) benefit	(1,772)	(6,962)	(748)	(28,426)
Total other comprehensive income	2,874	11,286	1,209	46,069
Ending Balance	$ (53,470)	$ 13,453	$ (53,470)	$ 13,453