Other Comprehensive Income (Loss) (Component of Other Comprehensive Income (Loss)) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Before Tax Amount	$ (115,245)	$ 33,412	$ 208,015
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Before Tax Amount	(35,682)	(657)
Securities available for sale and transferred securities, Reclassification adjustment for (gains) losses included in net income, Before Tax Amount	(1,176)	(4,314)	(6,414)
Total securities available for sale and transferred securities	(152,103)	28,441	201,601
Defined-benefit post-retirement benefit plans, Change in the net actuarial gain/loss, Before Tax Amount	35,293	(9,405)	(22,463)
Derivatives, Change in the accumulated gain/loss on effective cash flow hedge derivatives, Before Tax Amount	(49)	(783)	(2,321)
Derivatives, Reclassification adjustments for (gains) losses included in net income, Interest rate swaps on variable-rate loans, Before Tax Amount	(37,380)	(37,380)	(37,380)
Derivatives, Reclassification adjustments for (gains) losses included in net income, Interest rate swap on junior subordinated deferrable interest debentures, Before Tax Amount	4,064	4,224	4,386
Total derivatives	(33,365)	(33,939)	(35,315)
Other comprehensive income (loss), before tax	(150,175)	(14,903)	143,823
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Tax Expense (Benefit)	(40,335)	11,694	72,806
Securities available for sale and transferred securities, change in net unrealized gain on securities transfers to held-to-maturity, tax expense benefit	(12,489)	(230)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Tax Expense (Benefit)	(412)	(1,510)	(2,245)
Total securities available for sale and transferred securities, Tax Expense (Benefit)	(53,236)	9,954	70,561
Defined-benefit post-retirement benefit plans, Change in the net actuarial gain/loss, Tax Expense (Benefit)	12,353	(3,292)	(7,862)
Derivatives, Change in the accumulated gain/loss on effective cash flow hedge derivatives, Tax Expense (Benefit)	(17)	(274)	(812)
Derivatives, Reclassification adjustments for (gains) losses included in net income, Interest rate swaps on variable-rate loans, Tax Expense (Benefit)	(13,083)	(13,083)	(13,083)
Derivatives, Reclassification adjustments for (gains) losses included in net income, Interest rate swap on junior subordinated deferrable interest debentures, Tax Expense (Benefit)	1,422	1,478	1,535
Derivatives, Total derivatives, Tax Expense, (Benefit)	(11,678)	(11,879)	(12,360)
Total other comprehensive income, Tax Expense (Benefit)	(52,561)	(5,217)	50,339
Securities available for sale and transferred securities, change in net unrealized gain/loss during the period, net of tax	(74,910)	21,718	135,209
Securities available for sale and transferred securities, change in net unrealized gain on securities transfers to held-to-maturity, net of tax	(23,193)	(427)
Securities available for sale and securities transferred, reclassification adjustment for net (gains) losses included in net income, net of tax	(764)	(2,804)	(4,169)
Total securities available for sale and transferred securities, net of tax	(98,867)	18,487	131,040
Defined-benefit post-retirement plans, Change in the net actuarial gain/loss, net of tax	22,940	(6,113)	(14,601)
Derivatives, Change in the accumulated gain/loss on effective cash flow hedge derivatives, net of tax	(32)	(509)	(1,509)
Derivatives, reclassification adjustment for (gains) losses included in net income, interest rate swaps on variable-rate loans, net of tax	(24,297)	(24,297)	(24,297)
Derivatives, reclassification adjustment for (gains) losses included in net income, interest rate swap on junior subordinated deferrable interest debentures, net of tax	2,642	2,746	2,851
Derivatives, Total derivatives, net of tax	(21,687)	(22,060)	(22,955)
Other comprehensive income (loss), net of tax	$ (97,614)	$ (9,686)	$ 93,484