CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension and other post retirement obligations:
Amortization of actuarial (gains)/losses included in net periodic pension cost, gross	$ (7,236)	$ (13,904)	$ 35,395
Tax effect	2,774	5,374	(13,841)
Amortization of actuarial (gains)/losses included in net periodic pension cost, net	(4,462)	(8,530)	21,554
Amortization of prior service cost included in net periodic pension cost, gross	(170)	(1,698)	(1,502)
Tax effect	65	657	588
Amortization of prior service cost included in net periodic pension cost, net	(105)	(1,041)	(914)
Other comprehensive (loss)/income related to pension and other post retirement obligations, net of taxes	(4,567)	(9,571)	20,640
Unrealized (losses)/gains on securities:
Net unrealized holding (losses)/gains arising during period, gross	(9,209)	106,040	(79,899)
Tax effect	2,289	(39,203)	30,385
Net unrealized holding (losses)/gains arising during period, net	(6,920)	66,837	(49,514)
Reclassification adjustment for net losses/(gains) included in net income, gross	4	0	(80,768)
Tax effect	(2)	0	29,756
Reclassification adjustment for net losses/(gains) included in net income, net	2	0	(51,012)
Unrealized holding loss, net related to securities transferred from held-to-maturity to available-for-sale, gross	0	0	(1,791)
Tax effect	0	0	797
Reclassification adjustment for net loss transferred from held-to-maturity to available-for-sale, net	0	0	(994)
Other comprehensive (loss)/income related to unrealized gains/(losses) on available-for-sale securities, net of taxes	(6,918)	66,837	(101,520)
Other comprehensive (loss)/income, net of tax	(11,485)	57,266	(80,880)
Net income	91,230	91,353	78,829
Comprehensive income/(loss)	79,745	148,619	(2,051)
Accumulated Other Comprehensive Income By Component:
Unrealized loss for pension and other postretirement obligations	(34,347)	(26,941)	(11,339)
Tax effect	13,064	10,225	4,194
Net unrealized loss for pension and other postretirement obligations	(21,283)	(16,716)	(7,145)
Unrealized gain/(loss) on available-for-sale securities	65,835	75,039	(31,002)
Tax effect	(25,317)	(27,603)	11,601
Net unrealized gain/(loss) on available-for-sale securities	40,518	47,436	(19,401)
Accumulated other comprehensive income/(loss)	$ 19,235	$ 30,720	$ (26,546)