Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	$ 179,403	[1]		$ 172,587	[2]
90 or More Days Past Due and Accruing	2,051			2,087
Non-accrual	140,069			130,148
Current	15,492,332			13,727,438
Total Loans and Leases	15,671,735	[3],[4]		13,900,025	[3],[4]	$ 12,699,776
Interest Receivable	43,100			38,400
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	71,298	[1]		83,406	[2],[5]
90 or More Days Past Due and Accruing	2,029		$ 2,000	2,039	[5]
Non-accrual	54,201			64,117	[5]
Current	3,989,703			3,425,769	[5]
Total Loans and Leases	4,061,001			3,509,175	[5]	3,361,425
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans and Leases	2,702,560			2,549,401		2,536,688
Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	2,565	[1]		1,395	[2]
90 or More Days Past Due and Accruing	0			0
Non-accrual	560			281
Current	246,597			74,236
Total Loans and Leases	249,162			75,631
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	50,640	[1]		56,495	[2]
90 or More Days Past Due and Accruing	0			0
Non-accrual	37,337			40,026
Current	2,402,758			2,417,275
Total Loans and Leases	2,453,398			2,473,770
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans and Leases	4,315,999			3,749,270		3,282,851
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	31,115	[1]		8,598	[2]
90 or More Days Past Due and Accruing	22			48
Non-accrual	27,037			6,449
Current	3,531,669			3,079,342
Total Loans and Leases	3,562,784			3,087,940
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	0	[1]		0	[2]
90 or More Days Past Due and Accruing	0			0
Non-accrual	0			0
Current	753,215			661,330
Total Loans and Leases	753,215			661,330
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans and Leases	3,991,649			3,554,428		3,058,362
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	19,016	[1]		17,755	[2]
90 or More Days Past Due and Accruing	0			0
Non-accrual	16,767			15,038
Current	3,673,408			3,302,652
Total Loans and Leases	3,692,424			3,320,407
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	3,461	[1]		3,659	[2]
90 or More Days Past Due and Accruing	0			0
Non-accrual	3,461			3,659
Current	295,764			230,362
Total Loans and Leases	299,225			234,021
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	1,308	[1]		1,279	[2]
90 or More Days Past Due and Accruing	0			0
Non-accrual	706			578
Current	599,218			536,472
Total Loans and Leases	600,526			537,751		$ 460,450
30 days or more days past due and accruing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Interest Receivable	600			500
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	23,751			28,331
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	10,365			11,410	[5]
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	1,390			704
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	9,061			11,393
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	768			1,948
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	0			0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	1,624			2,325
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	0			0
Financing Receivables, 30 to 59 Days Past Due [Member] | Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	543			551
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	13,532			12,021
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	4,703			5,840	[5]
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	615			410
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	4,242			5,076
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	3,288			153
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	0			0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	625			392
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	0			0
Financing Receivables, 60 to 89 Days Past Due [Member] | Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due and Non-accrual(1)	$ 59			$ 150

[1] At December 31, 2015(In thousands)30-59 DaysPast Due andAccruing60-89 DaysPast Due andAccruing90 or More Days Past Dueand AccruingNon-accrualTotal Past Due and Non-accrual(1)CurrentTotal Loansand LeasesResidential $10,365$4,703$2,029$54,201$71,298$3,989,703$4,061,001Consumer: Home equity 9,0614,242—37,33750,6402,402,7582,453,398Other consumer1,390615—5602,565246,597249,162Commercial: Commercial non-mortgage7683,2882227,03731,1153,531,6693,562,784Asset-based—————753,215753,215Commercial real estate: Commercial real estate1,624625—16,76719,0163,673,4083,692,424Commercial construction———3,4613,461295,764299,225Equipment financing54359—7061,308599,218600,526Total$23,751$13,532$2,051$140,069$179,403$15,492,332$15,671,735

[2] Loans and leases 30 days or more days past due and accruing exclude $0.6 million and $0.5 million of accrued interest receivable at December 31, 2015 and December 31, 2014, respectively.

[3] Accrued interest of $43.1 million and $38.4 million at December 31, 2015 and December 31, 2014, respectively, are not included in the loan and lease balances.

[4] Loan and lease balances include net deferred fees and unamortized premiums of $18.0 million and $10.6 million at December 31, 2015 and December 31, 2014, respectively.

[5] U.S. Government guaranteed loans of approximately $2.0 million were reclassified from non-accrual to over 90 days past due and accruing reflective of a policy change effective in the first quarter of 2015.