Stock Option Plans - Summary of Options Outstanding (Details) (USD $)	12 Months Ended
Dec. 31, 2014
Number outstanding	1,357,813
Number exercisable	880,743
$6.81-$10.25
Range of exercise prices, lower range	$ 6.81
Range of exercise prices, upper range	$ 10.25
Number outstanding	500,188
Options outstanding weighted-average remaining contractual life (years)	6 years
Options outstanding weighted-average exercise price	$ 9.44
Number exercisable	430,243
Options exercisable weighted-average exercise price	$ 9.37
$10.26-$13.62
Range of exercise prices, lower range	$ 10.26
Range of exercise prices, upper range	$ 13.62
Number outstanding	302,875
Options outstanding weighted-average remaining contractual life (years)	6 years
Options outstanding weighted-average exercise price	$ 11.70
Number exercisable	211,625
Options exercisable weighted-average exercise price	$ 11.97
$13.63-$15.33
Range of exercise prices, lower range	$ 13.63
Range of exercise prices, upper range	$ 15.33
Number outstanding	309,750
Options outstanding weighted-average remaining contractual life (years)	5 years
Options outstanding weighted-average exercise price	$ 14.38
Number exercisable	188,375
Options exercisable weighted-average exercise price	$ 14.72
$15.34-$17.03
Range of exercise prices, lower range	$ 15.34
Range of exercise prices, upper range	$ 17.03
Number outstanding	245,000
Options outstanding weighted-average remaining contractual life (years)	8 years
Options outstanding weighted-average exercise price	$ 16.56
Number exercisable	50,500
Options exercisable weighted-average exercise price	$ 16.14

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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- Definition

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

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (g)

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

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- Definition

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

-Paragraph 2

-Subparagraph (c)(iii)

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

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- Definition

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

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)-(ii)

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

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- Definition

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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-Paragraph 2

-Subparagraph (c)(1)(i)-(ii)

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

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- Definition

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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

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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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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