Accumulated Other Comprehensive Loss (Components Of AOCI) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Loss, Beginning Balance			$ (37,258,000)
Sale of securities for which other-than-temporary impairment was previously recognized, net of tax	0	0	0	3,180,000
Interest Expense	25,128,000	31,927,000	77,636,000	94,930,000
Net realized loss (gain) on sales of securities	2,000	31,000	(51,000)	1,633,000
Accumulated Other Comprehensive Loss, Ending Balance	(62,948,000)		(62,948,000)
Unrealized Gains (Losses) On Investment Securities With OTTI [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Loss, Beginning Balance	(750,000)	(1,461,000)	(839,000)	(2,564,000)
AOCI Before Reclassifications, Net Of Tax	150,000	86,000	(76,000)	(1,826,000)
Sale of securities for which other-than-temporary impairment was previously recognized, net of tax		0		2,892,000
Net Change In AOCI	150,000	86,000	239,000	1,189,000
Accumulated Other Comprehensive Loss, Ending Balance	(600,000)	(1,375,000)	(600,000)	(1,375,000)
Unrealized Gains (Losses) On Investment Securities With OTTI [Member] | Amounts Reclassified From AOCI [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Interest Expense	0	0	0	0
Net realized loss (gain) on sales of securities	0	0	485,000	190,000
Total Before Income Taxes	0	0	485,000	190,000
Less: Income Taxes	0	0	(170,000)	(67,000)
Net Of Income Taxes	0	0	315,000	123,000
Unrealized Gains (Losses) On Investment Securities All Other [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Loss, Beginning Balance	(414,000)	27,692,000	37,521,000	23,388,000
AOCI Before Reclassifications, Net Of Tax	1,994,000	13,355,000	(35,660,000)	18,794,000
Sale of securities for which other-than-temporary impairment was previously recognized, net of tax		0		0
Net Change In AOCI	1,993,000	13,335,000	(35,942,000)	17,639,000
Accumulated Other Comprehensive Loss, Ending Balance	1,579,000	41,027,000	1,579,000	41,027,000
Unrealized Gains (Losses) On Investment Securities All Other [Member] | Amounts Reclassified From AOCI [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Interest Expense	0	0	0	0
Net realized loss (gain) on sales of securities	(2,000)	(31,000)	(434,000)	(1,823,000)
Total Before Income Taxes	(2,000)	(31,000)	(434,000)	(1,823,000)
Less: Income Taxes	1,000	11,000	152,000	668,000
Net Of Income Taxes	(1,000)	(20,000)	(282,000)	(1,155,000)
Unrealized Gains (Losses) On Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Loss, Beginning Balance	(25,437,000)	(35,883,000)	(34,636,000)	(33,403,000)
AOCI Before Reclassifications, Net Of Tax	(2,434,000)	(4,541,000)	784,000	(12,643,000)
Sale of securities for which other-than-temporary impairment was previously recognized, net of tax		0		0
Net Change In AOCI	831,000	(1,659,000)	10,030,000	(4,139,000)
Accumulated Other Comprehensive Loss, Ending Balance	(24,606,000)	(37,542,000)	(24,606,000)	(37,542,000)
Unrealized Gains (Losses) On Cash Flow Hedges [Member] | Amounts Reclassified From AOCI [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Interest Expense	5,023,000	4,434,000	14,225,000	13,083,000
Net realized loss (gain) on sales of securities	0	0	0	0
Total Before Income Taxes	5,023,000	4,434,000	14,225,000	13,083,000
Less: Income Taxes	(1,758,000)	(1,552,000)	(4,979,000)	(4,579,000)
Net Of Income Taxes	3,265,000	2,882,000	9,246,000	8,504,000
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Loss, Beginning Balance	(39,321,000)	(33,475,000)	(39,304,000)	(33,475,000)
AOCI Before Reclassifications, Net Of Tax	0	0	(17,000)	0
Sale of securities for which other-than-temporary impairment was previously recognized, net of tax		0		0
Net Change In AOCI	0	0	(17,000)	0
Accumulated Other Comprehensive Loss, Ending Balance	(39,321,000)	(33,475,000)	(39,321,000)	(33,475,000)
Post-Retirement Benefits [Member] | Amounts Reclassified From AOCI [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Interest Expense	0	0	0	0
Net realized loss (gain) on sales of securities	0	0	0	0
Total Before Income Taxes	0	0	0	0
Less: Income Taxes	0	0	0	0
Net Of Income Taxes	0	0	0	0
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated Other Comprehensive Loss, Beginning Balance	(65,922,000)	(43,127,000)	(37,258,000)	(46,054,000)
AOCI Before Reclassifications, Net Of Tax	(290,000)	8,900,000	(34,969,000)	4,325,000
Sale of securities for which other-than-temporary impairment was previously recognized, net of tax		0		2,892,000
Net Change In AOCI	2,974,000	11,762,000	(25,690,000)	14,689,000
Accumulated Other Comprehensive Loss, Ending Balance	(62,948,000)	(31,365,000)	(62,948,000)	(31,365,000)
Accumulated Other Comprehensive Loss [Member] | Amounts Reclassified From AOCI [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Interest Expense	5,023,000	4,434,000	14,225,000	13,083,000
Net realized loss (gain) on sales of securities	(2,000)	(31,000)	51,000	(1,633,000)
Total Before Income Taxes	5,021,000	4,403,000	14,276,000	11,450,000
Less: Income Taxes	(1,757,000)	(1,541,000)	(4,997,000)	(3,978,000)
Net Of Income Taxes	$ 3,264,000	$ 2,862,000	$ 9,279,000	$ 7,472,000