Long -Term Borrowings (Debentures And Related Weighted Average Interest Rates) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Debentures Amount	$ 198,515	$ 203,557
Century Trust [Member]
Debt Instrument [Line Items]
Debentures Amount	8,800	8,800
Weighted-Average Rate	10.88%	10.88%
Sequoia Trust I [Member]
Debt Instrument [Line Items]
Debentures Amount	2,064	7,220
Weighted-Average Rate	10.18%	10.18%
United Statutory Trust III [Member]
Debt Instrument [Line Items]
Debentures Amount	20,619	20,619
Weighted-Average Rate	3.16%	3.41%
United Statutory Trust IV [Member]
Debt Instrument [Line Items]
Debentures Amount	25,774	25,774
Weighted-Average Rate	3.16%	3.28%
United Statutory Trust V [Member]
Debt Instrument [Line Items]
Debentures Amount	51,547	51,547
Weighted-Average Rate	1.91%	6.67%
United Statutory Trust VI [Member]
Debt Instrument [Line Items]
Debentures Amount	30,928	30,928
Weighted-Average Rate	1.61%	6.60%
Premier Statutory Trust II [Member]
Debt Instrument [Line Items]
Debentures Amount	6,186	6,186
Weighted-Average Rate	3.44%	3.50%
Premier Statutory Trust III [Member]
Debt Instrument [Line Items]
Debentures Amount	8,248	8,248
Weighted-Average Rate	2.05%	2.29%
Premier Statutory Trust IV [Member]
Debt Instrument [Line Items]
Debentures Amount	14,433	14,433
Weighted-Average Rate	1.86%	2.12%
Premier Statutory Trust V [Member]
Debt Instrument [Line Items]
Debentures Amount	10,310	10,310
Weighted-Average Rate	1.92%	6.62%
Centra Statutory Trust I [Member]
Debt Instrument [Line Items]
Debentures Amount	9,803	9,746
Weighted-Average Rate	2.60%	2.85%
Centra Statutory Trust II [Member]
Debt Instrument [Line Items]
Debentures Amount	$ 9,803	$ 9,746
Weighted-Average Rate	1.99%	2.05%