Employee and Non-Employee Director Stock and Benefit Plans (Detail 2) (USD $)	12 Months Ended
Dec. 31, 2014
Range of Exercise Prices
Number Outstanding (in shares)	306,853
Weighted Average Remaining Contractual Life	2 years 11 months 19 days
Weighted Average Exercise Price (in dollars per share)	$ 17.23
Number Exercisable (in shares)	306,853
Weighted Average Exercise Price (in dollars per share)	$ 17.23
Range Of Exercise Prices From 12.17 to 15.82 \| Stock options
Range of Exercise Prices
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	$ 12.17
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 15.82
Number Outstanding (in shares)	51,198
Weighted Average Remaining Contractual Life	1 year 6 months 29 days
Weighted Average Exercise Price (in dollars per share)	$ 12.17
Number Exercisable (in shares)	51,198
Weighted Average Exercise Price (in dollars per share)	$ 12.17
Range Of Exercise Prices From 15.83 to 17.43
Range of Exercise Prices
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	$ 15.83
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 17.43
Number Outstanding (in shares)	34,447
Weighted Average Remaining Contractual Life	6 months 7 days
Weighted Average Exercise Price (in dollars per share)	$ 16.30
Number Exercisable (in shares)	34,447
Weighted Average Exercise Price (in dollars per share)	$ 16.30
Range Of Exercise Prices From 17.44 to 18.70 \| Stock options
Range of Exercise Prices
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	$ 17.44
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 18.70
Number Outstanding (in shares)	28,475
Weighted Average Remaining Contractual Life	5 months 23 days
Weighted Average Exercise Price (in dollars per share)	$ 17.44
Number Exercisable (in shares)	28,475
Weighted Average Exercise Price (in dollars per share)	$ 17.44
Range Of Exercise Prices From 18.71 to 18.71 \| Stock options
Range of Exercise Prices
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	$ 18.71
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 18.71
Number Outstanding (in shares)	192,733
Weighted Average Remaining Contractual Life	4 years 1 month 24 days
Weighted Average Exercise Price (in dollars per share)	$ 18.71
Number Exercisable (in shares)	192,733
Weighted Average Exercise Price (in dollars per share)	$ 18.71

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

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

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

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-Publisher FASB

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Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

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