Fair Value of Financial Instruments - Summary of Significant Unobservable Inputs Used in Fair Value Measurement of Level 3 Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	$ 126,226	$ 126,066	$ 146,817
Investment securities available for sale, Recurring	619,746	554,693	380,348
Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	35,373	33,351	39,885
Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	38,426	45,893	62,178
Purchased Non-Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	16,598	4,276
Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	126,226	126,066	146,817
Investment securities available for sale, Recurring	2,000	2,000	2,000
Level 3 [Member] | Impaired Loans Carried at Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Technique	Third party appraisals and discounted cash flows
Level 3 [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	35,373	33,351	39,885
Valuation Technique	Third party appraisals
Level 3 [Member] | Purchased Non-Covered Loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Technique	Third party appraisals
Level 3 [Member] | Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	38,426	45,893	62,178
Valuation Technique	Third party appraisals
Level 3 [Member] | Purchased Non-Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	16,598	4,276
Level 3 [Member] | Fair Value Measurement, Recurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment securities available for sale, Recurring	2,000
Valuation Technique	Discounted par values
Level 3 [Member] | Fair Value Measurement, Nonrecurring [Member] | Impaired Loans Carried at Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	35,289
Level 3 [Member] | Fair Value Measurement, Nonrecurring [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	35,373
Level 3 [Member] | Fair Value Measurement, Nonrecurring [Member] | Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	38,426
Level 3 [Member] | Fair Value Measurement, Nonrecurring [Member] | Purchased Non-Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Disclosure, Nonrecurring	$ 16,598
Level 3 [Member] | Minimum [Member] | Impaired Loans Carried at Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	4.00%
Level 3 [Member] | Minimum [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	10.00%
Level 3 [Member] | Minimum [Member] | Purchased Non-Covered Loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	21.00%
Level 3 [Member] | Minimum [Member] | Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	10.00%
Level 3 [Member] | Minimum [Member] | Fair Value Measurement, Recurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	0.00%
Level 3 [Member] | Maximum [Member] | Impaired Loans Carried at Fair Value [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	7500.00%
Level 3 [Member] | Maximum [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	7400.00%
Level 3 [Member] | Maximum [Member] | Purchased Non-Covered Loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	7000.00%
Level 3 [Member] | Maximum [Member] | Covered Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	9000.00%
Level 3 [Member] | Maximum [Member] | Fair Value Measurement, Recurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs discount rate range	0.00%