Loans (Activity in Allowance for Loan Losses by Portfolio Segment) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 110,147	$ 126,316	$ 125,309
Provision for loan losses	10,080	27,445	43,611
Charge-offs	(33,040)	(56,685)	(53,423)
Recoveries	17,266	13,071	10,819
Net charge-offs	(15,774)	(43,614)	(42,604)
Ending balance	104,453	110,147	126,316
Loans individually evaluated for impairment	17,537	19,549	40,539
Loans collectively evaluated for impairment	86,916	90,598	85,777
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	42,774	57,789	57,394
Provision for loan losses	25,013	14,137	28,925
Charge-offs	(18,493)	(33,678)	(31,324)
Recoveries	4,870	4,526	2,794
Net charge-offs	(13,623)	(29,152)	(28,530)
Ending balance	54,164	42,774	57,789
Loans individually evaluated for impairment	13,171	15,829	31,948
Loans collectively evaluated for impairment	40,993	26,945	25,841
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	20,912	28,534	28,514
Provision for loan losses	7,658	1,812	6,564
Charge-offs	(3,951)	(10,776)	(7,524)
Recoveries	4,727	1,342	980
Net charge-offs	776	(9,434)	(6,544)
Ending balance	29,346	20,912	28,534
Loans individually evaluated for impairment	4,366	3,625	8,591
Loans collectively evaluated for impairment	24,980	17,287	19,943
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	3,540	3,223	2,560
Provision for loan losses	2,350	2,610	2,722
Charge-offs	(1,495)	(2,789)	(2,682)
Recoveries	857	496	623
Net charge-offs	(638)	(2,293)	(2,059)
Ending balance	5,252	3,540	3,223
Loans individually evaluated for impairment		95
Loans collectively evaluated for impairment	5,252	3,445	3,223
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	12,635	11,974	16,929
Provision for loan losses	(6,839)	3,396	516
Charge-offs	(9,101)	(9,442)	(11,893)
Recoveries	6,812	6,707	6,422
Net charge-offs	(2,289)	(2,735)	(5,471)
Ending balance	3,507	12,635	11,974
Loans collectively evaluated for impairment	3,507	12,635	11,974
Unallocated Financing Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	30,286	24,796	19,912
Provision for loan losses	(18,102)	5,490	4,884
Ending balance	12,184	30,286	24,796
Loans collectively evaluated for impairment	$ 12,184	$ 30,286	$ 24,796