Deposits - Interest Expense on Deposits (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Banking and Thrift [Abstract]
Savings deposits	$ 2,092	$ 1,709	$ 1,039
NOW and money market accounts	12,205	10,106	8,046
Certificates of deposits	5,144	5,132	5,436
Total interest expense on deposits	$ 19,441	$ 16,947	$ 14,521

No definition available.

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- Definition

Aggregate amount of interest expense on all deposits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.6)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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- Definition

The aggregate interest expense incurred on the following for deposits in domestic offices: (1) transaction accounts (NOW, and telephone and preauthorized transfer accounts), (2) money market deposits and (3) savings deposits.

+ References

+ Details

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- Definition

Interest expense incurred on all savings account deposits.

+ References

+ Details

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- Definition

The aggregate interest expense incurred on time deposits, including certificates of deposits, in domestic offices.

+ References

+ Details

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