Non-Covered Loans and Lease Finance Receivables and Allowance for Loan Losses - Loans Modified as Troubled Debt Restructurings (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2011 Contract	Dec. 31, 2013 Non-Covered Loans [Member] Contract	Dec. 31, 2012 Non-Covered Loans [Member] Contract	Dec. 31, 2011 Commercial and Industrial [Member] Contract	Dec. 31, 2013 Commercial and Industrial [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Commercial and Industrial [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2013 Commercial and Industrial [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2012 Commercial and Industrial [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2011 Commercial Real Estate Owner Occupied [Member] Contract	Dec. 31, 2013 Commercial Real Estate Owner Occupied [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Commercial Real Estate Owner Occupied [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2013 Commercial Real Estate Owner Occupied [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2012 Commercial Real Estate Owner Occupied [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2011 Single Family Mortgage Loans [Member] Contract	Dec. 31, 2013 Single Family Mortgage Loans [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Single Family Mortgage Loans [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2013 Single Family Mortgage Loans [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2012 Single Family Mortgage Loans [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2011 Dairy & Livestock and Agribusiness [Member] Contract	Dec. 31, 2013 Dairy & Livestock and Agribusiness [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Dairy & Livestock and Agribusiness [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2013 Dairy & Livestock and Agribusiness [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2012 Dairy & Livestock and Agribusiness [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2011 Commercial Real Estate Non-owner Occupied [Member] Contract	Dec. 31, 2012 Commercial Real Estate Non-owner Occupied [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Commercial Real Estate Non-owner Occupied [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2011 Construction Speculative [Member] Contract	Dec. 31, 2012 Construction Speculative [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Construction Speculative [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2012 Municipal Lease Finance Receivables [Member] Interest Rate Reduction [Member] Contract	Dec. 31, 2012 Municipal Lease Finance Receivables [Member] Change in Amortization Period or Maturity [Member] Contract	Dec. 31, 2011 Construction Non-speculative [Member] Contract
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans		25	18	31	5		1	4	8	3			1	6	6	3	1			5			10	7	3	1	4	2		1		2	1
Troubled debt restructurings, pre-modification outstanding recorded investment	$ 0	$ 56,592,000	$ 29,069,000	$ 37,221,000	$ 1,673,000		$ 80,000	$ 621,000	$ 2,301,000	$ 3,195,000			$ 168,000	$ 4,225,000	$ 2,162,000	$ 1,365,000	$ 399,000			$ 11,750,000			$ 26,915,000	$ 9,447,000	$ 11,707,000	$ 3,378,000	$ 5,906,000	$ 16,886,000		$ 10,966,000		$ 519,000	$ 9,219,000
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment		56,290,000	29,069,000	37,221,000	1,372,000		80,000	621,000	2,301,000	3,195,000			168,000	4,225,000	2,161,000	1,365,000	399,000			11,750,000			26,915,000	9,447,000	11,707,000	3,378,000	5,906,000	16,886,000		10,966,000		519,000	9,219,000
Troubled debt restructurings, Outstanding Recorded Investment		49,851,000	24,719,000	34,956,000	1,224,000		66,000	570,000	1,817,000	3,067,000			138,000	3,903,000	2,049,000	1,349,000	398,000			8,662,000			22,662,000	9,184,000	10,236,000	3,359,000	5,303,000	15,394,000		10,663,000		263,000	9,219,000
Troubled debt restructurings, Financial Effect Resulting From Modifications			$ 244,000	$ 3,000				$ 95,000	$ 3,000														$ 149,000