Loan and Lease Finance Receivables and Allowance for Loan Losses - Schedule of Recorded Investment in Non-Covered Past Due and Nonaccrual Loans and Loans Past Due by Class of Loans (Detail) (Non-Covered Loans [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
30-59 Days Past Due	$ 1,632	$ 422
60-89 Days Past Due		465
90+ Days Past Due and Accruing
Total Past Due and Accruing	1,632	887
Nonaccrual	53,351	57,997
Current	3,122,988	3,200,354
Total Loans and Financing Receivables	3,177,971	3,259,238
Commercial and Industrial [Member]
30-59 Days Past Due	373	233
60-89 Days Past Due		457
90+ Days Past Due and Accruing
Total Past Due and Accruing	373	690
Nonaccrual	5,012	3,136
Current	519,759	543,596
Total Loans and Financing Receivables	525,144	547,422
Commercial Real Estate Owner occupied [Member]
30-59 Days Past Due	683
60-89 Days Past Due
90+ Days Past Due and Accruing
Total Past Due and Accruing	683
Nonaccrual	4,395	5,415
Current	701,565	698,552
Total Loans and Financing Receivables	706,643	703,967
Commercial real estate Non-owner occupied [Member]
30-59 Days Past Due	568
60-89 Days Past Due
90+ Days Past Due and Accruing
Total Past Due and Accruing	568
Nonaccrual	14,215	15,624
Current	1,287,320	1,270,516
Total Loans and Financing Receivables	1,302,103	1,286,140
Construction Speculative [Member]
60-89 Days Past Due
90+ Days Past Due and Accruing
Nonaccrual	10,494	10,663
Current	16,026	27,231
Total Loans and Financing Receivables	26,520	37,894
Construction Non-speculative [Member]
60-89 Days Past Due
90+ Days Past Due and Accruing
Current	19,845	21,827
Total Loans and Financing Receivables	19,845	21,827
SFR Mortgage [Member]
30-59 Days Past Due		107
60-89 Days Past Due
90+ Days Past Due and Accruing
Total Past Due and Accruing		107
Nonaccrual	11,423	13,102
Current	168,700	146,079
Total Loans and Financing Receivables	180,123	159,288
Dairy & Livestock and Agribusiness [Member]
60-89 Days Past Due
90+ Days Past Due and Accruing
Nonaccrual	7,655
Current	251,472
Total Loans and Financing Receivables	259,127
Municipal Lease Finance Receivables [Member]
60-89 Days Past Due
90+ Days Past Due and Accruing
Current	105,246	105,767
Total Loans and Financing Receivables	105,246	105,767
Consumer and Other Loans [Member]
30-59 Days Past Due	8	82
60-89 Days Past Due		8
90+ Days Past Due and Accruing
Total Past Due and Accruing	8	90
Nonaccrual	157	215
Current	53,055	59,968
Total Loans and Financing Receivables	53,220	60,273
Dairy & livestock and agribusiness [Member]
90+ Days Past Due and Accruing
Nonaccrual		9,842
Current		326,818
Total Loans and Financing Receivables		$ 336,660