Amortized Cost and Aggregate Fair Value of Held-to-Maturity Securities, Including Gross Unrealized Gains and Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 72,596	$ 57,948
Unrealized Gains	434	29
Unrealized Losses		(88)
Fair Value	73,030	57,889
U.S. Agency securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	61,895	46,987
Unrealized Gains	366	22
Unrealized Losses		(54)
Fair Value	62,261	46,955
Corporate securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,511	10,582
Unrealized Gains	67
Unrealized Losses		(34)
Fair Value	10,578	10,548
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	190	379
Unrealized Gains	1	7
Fair Value	$ 191	$ 386

Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity.

+ References

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Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

+ References

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Fair value of investments in debt securities classified as held-to-maturity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-Section 50

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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