Accumulated Other Comprehensive Loss (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of investment securities	$ 16	$ 5	$ 53	$ 612
Income tax (expense)/benefit	(3,600)	(9,600)	(24,300)	(26,800)
Net income	10,732	24,467	59,701	61,326
Net Income (Loss)	(1,882)	(707)	(1,132)	(2,120)
Unrealized gains (losses) on securities available-for-sale, net of tax [Member] | Reclassification out of accumulated other comprehensive income (loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of investment securities	16	5	53	612
Income tax (expense)/benefit	(6)	(2)	(18)	(214)
Net income	10	3	35	398
Amortization of defined benefit pension plan items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries, wages and employee benefits (operating expenses)	(2,895)	(1,087)	(1,742)	(3,261)
Income tax (expense)/benefit	$ 1,013	$ 380	$ 610	$ 1,141