Stock-Based Compensation Plans (Employee stock purchase plan) - Additional Information (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Maximum number of shares issuable under the ESPP	250		250
Percentage of share purchase price			85.00%
Discount on the share purchases			15.00%
Employee stock purchase plan description, compensation expense	$ 56	$ 39	$ 110	$ 78

Share based compensation arrangement by share based payment award discounted purchase price offering date.

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- References

No definition available.

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- Definition

The amount of plan compensation cost recognized during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 40

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

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- Definition

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 40

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

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- Definition

Discount rate from fair value on purchase date that participants pay for shares.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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