Long-Term Borrowings and Subordinated Debt - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-term borrowings		$ 21,600,000	$ 19,300,000
Total loans pledged as collateral			2,300,000,000
Percentage of maximum borrowing capacity for any credit exposure			70.00%
Maximum eligible borrowing based on qualifying collateral			1,300,000,000.0
Maximum borrowing capacity			1,600,000,000.0
Capital lease			200,000us-gaap_DebtAndCapitalLeaseObligations
Percentage of equity owned			100.00%
Early repayment of junior subordinated debt	$ 45,000,000	$ 45,000,000

Line of credit facility maximum borrowing capacity percentage.

No definition available.

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- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

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-Subparagraph (SX 210.9-03.13,16)

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- Definition

The cash outflow from the repayment of long-term borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in case of liquidation of the entity's assets before its maturity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

+ References

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- Definition

Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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-Section 02

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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