Loans and Allowance for Loan Losses - Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile Based on Payment Activity (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	$ 1,561,487	$ 1,581,597
Consumer [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,554,525	1,574,685
Consumer [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	6,962	6,912
Consumer [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,407,712	1,409,130
Consumer [Member] | Originated loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,402,732	1,404,032
Consumer [Member] | Originated loans [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	4,980	5,098
Consumer [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	107,501	119,603
Consumer [Member] | Acquired loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	105,519	117,789
Consumer [Member] | Acquired loans [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,982	1,814
Consumer [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	46,274	52,864
Consumer [Member] | Covered Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	46,274	52,864
Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	5,198,029	5,064,222
Commercial Non Real Estate Credit Exposure [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	4,353,549	4,113,835
Commercial Non Real Estate Credit Exposure [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	830,211	926,998
Commercial Non Real Estate Credit Exposure [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	14,269	23,389
Commercial Non Real Estate Credit Exposure [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	4,987,005	4,846,929
Commercial Non Real Estate Credit Exposure [Member] | Pass [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	4,222,077	3,990,318
Commercial Non Real Estate Credit Exposure [Member] | Pass [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	761,925	846,135
Commercial Non Real Estate Credit Exposure [Member] | Pass [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	3,003	10,476
Commercial Non Real Estate Credit Exposure [Member] | Pass-Watch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	99,353	90,848
Commercial Non Real Estate Credit Exposure [Member] | Pass-Watch [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	66,110	46,734
Commercial Non Real Estate Credit Exposure [Member] | Pass-Watch [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	33,235	44,105
Commercial Non Real Estate Credit Exposure [Member] | Pass-Watch [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	8	9
Commercial Non Real Estate Credit Exposure [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	45,039	64,624
Commercial Non Real Estate Credit Exposure [Member] | Special Mention [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	22,873	41,812
Commercial Non Real Estate Credit Exposure [Member] | Special Mention [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	19,253	19,915
Commercial Non Real Estate Credit Exposure [Member] | Special Mention [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	2,913	2,897
Commercial Non Real Estate Credit Exposure [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	65,156	60,063
Commercial Non Real Estate Credit Exposure [Member] | Substandard [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	41,569	34,276
Commercial Non Real Estate Credit Exposure [Member] | Substandard [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	15,242	16,125
Commercial Non Real Estate Credit Exposure [Member] | Substandard [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	8,345	9,662
Commercial Non Real Estate Credit Exposure [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,476	1,758
Commercial Non Real Estate Credit Exposure [Member] | Doubtful [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	920	695
Commercial Non Real Estate Credit Exposure [Member] | Doubtful [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	556	718
Commercial Non Real Estate Credit Exposure [Member] | Doubtful [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity		345
Commercial Non Real Estate Credit Exposure [Member] | Loss [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Commercial Non Real Estate Credit Exposure [Member] | Loss [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Commercial Non Real Estate Credit Exposure [Member] | Loss [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Commercial Non Real Estate Credit Exposure [Member] | Loss [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	978,798	915,540
Construction Credit Exposure [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	824,837	752,381
Construction Credit Exposure [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	134,443	142,931
Construction Credit Exposure [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	19,518	20,228
Construction Credit Exposure [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	883,411	822,034
Construction Credit Exposure [Member] | Pass [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	780,621	709,261
Construction Credit Exposure [Member] | Pass [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	101,172	112,773
Construction Credit Exposure [Member] | Pass [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,618
Construction Credit Exposure [Member] | Pass-Watch [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	10,843	10,950
Construction Credit Exposure [Member] | Pass-Watch [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	7,746	7,817
Construction Credit Exposure [Member] | Pass-Watch [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,879	1,907
Construction Credit Exposure [Member] | Pass-Watch [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,218	1,226
Construction Credit Exposure [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	16,885	13,611
Construction Credit Exposure [Member] | Special Mention [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	4,156	3,926
Construction Credit Exposure [Member] | Special Mention [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	12,459	9,409
Construction Credit Exposure [Member] | Special Mention [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	270	276
Construction Credit Exposure [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	66,167	61,717
Construction Credit Exposure [Member] | Substandard [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	32,314	31,377
Construction Credit Exposure [Member] | Substandard [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	18,933	18,842
Construction Credit Exposure [Member] | Substandard [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	14,920	11,498
Construction Credit Exposure [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,492	7,228
Construction Credit Exposure [Member] | Doubtful [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Construction Credit Exposure [Member] | Doubtful [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Construction Credit Exposure [Member] | Doubtful [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity	1,492	7,228
Construction Credit Exposure [Member] | Loss [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Construction Credit Exposure [Member] | Loss [Member] | Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Construction Credit Exposure [Member] | Loss [Member] | Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity
Construction Credit Exposure [Member] | Loss [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity