Borrowings - Summary of Information Pertaining to Borrowings (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Long Term And Short Term Debt [Line Items]
Short-term borrowings	$ 246,294us-gaap_ShortTermBorrowings	$ 320,605us-gaap_ShortTermBorrowings
Long-term borrowings	69,457us-gaap_LongTermDebt	65,061us-gaap_LongTermDebt
Total Borrowings	315,751	385,666
Short-term borrowings, Weighted Average Rate	0.27%	0.27%
Long-term borrowings, Weighted Average Rate	2.94%	2.79%
Total Borrowings, Weighted Average Rate	0.86%us-gaap_DebtWeightedAverageInterestRate	0.70%us-gaap_DebtWeightedAverageInterestRate
Securities Sold under Repurchase Agreements [Member]
Long Term And Short Term Debt [Line Items]
Short-term borrowings	46,721	30,605
Short-term borrowings, Weighted Average Rate	0.01%	0.01%
Short-Term Borrowings [Member]
Long Term And Short Term Debt [Line Items]
Short-term borrowings	199,573	290,000
Short-term borrowings, Weighted Average Rate	0.33%	0.31%
Other Long-Term Borrowings [Member]
Long Term And Short Term Debt [Line Items]
Long-term borrowings	18,838	19,442
Long-term borrowings, Weighted Average Rate	2.92%	3.00%
Junior Subordinated Debt Securities [Member]
Long Term And Short Term Debt [Line Items]
Long-term borrowings	$ 50,619	$ 45,619
Long-term borrowings, Weighted Average Rate	2.95%	2.70%

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

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- Definition

Weighted average interest rate of long-term debt outstanding.

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No definition available.

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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- Definition

Weighted average interest rate of short-term debt outstanding.

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