Common Stock and Share-Based Compensation - Summary Options Outstanding and Exercisable (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
$8.96 to $10.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Lower limit	$ 8.96
Exercise price range, Upper limit	$ 10.44
Number Outstanding, Options Outstanding	391,189
Weighted-Average Remaining Contractual Life, Options Outstanding	6 years 9 months
Weighted-Average Exercise Price, Options Outstanding	$ 9.86
Number Exercisable, Options Exercisable	316,998
Weighted-Average Exercise Price, Options Exercisable	$ 9.86
12.60 to 16.98
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Lower limit	$ 12.60
Exercise price range, Upper limit	$ 16.98
Number Outstanding, Options Outstanding	336,156
Weighted-Average Remaining Contractual Life, Options Outstanding	3 years 7 months 6 days
Weighted-Average Exercise Price, Options Outstanding	$ 14.37
Number Exercisable, Options Exercisable	323,808
Weighted-Average Exercise Price, Options Exercisable	$ 14.41
17.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Upper limit	$ 17.36
Number Outstanding, Options Outstanding	570,655
Weighted-Average Remaining Contractual Life, Options Outstanding	3 years 10 months 17 days
Weighted-Average Exercise Price, Options Outstanding	$ 17.36
Number Exercisable, Options Exercisable	570,655
Weighted-Average Exercise Price, Options Exercisable	$ 17.36
17.48 to 21.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Lower limit	$ 17.48
Exercise price range, Upper limit	$ 21.90
Number Outstanding, Options Outstanding	207,373
Weighted-Average Remaining Contractual Life, Options Outstanding	1 year 3 months 11 days
Weighted-Average Exercise Price, Options Outstanding	$ 21.04
Number Exercisable, Options Exercisable	207,373
Weighted-Average Exercise Price, Options Exercisable	$ 21.04
21.96
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Upper limit	$ 21.96
Number Outstanding, Options Outstanding	436,780
Weighted-Average Remaining Contractual Life, Options Outstanding	2 years 10 months 21 days
Weighted-Average Exercise Price, Options Outstanding	$ 21.96
Number Exercisable, Options Exercisable	436,780
Weighted-Average Exercise Price, Options Exercisable	$ 21.96
22.22
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Upper limit	$ 22.22
Number Outstanding, Options Outstanding	825,497
Weighted-Average Remaining Contractual Life, Options Outstanding	1 year 0 months 4 days
Weighted-Average Exercise Price, Options Outstanding	$ 22.22
Number Exercisable, Options Exercisable	825,497
Weighted-Average Exercise Price, Options Exercisable	$ 22.22
23.08 to 25.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Lower limit	$ 23.08
Exercise price range, Upper limit	$ 25.18
Number Outstanding, Options Outstanding	265,438
Weighted-Average Remaining Contractual Life, Options Outstanding	2 years 9 months 26 days
Weighted-Average Exercise Price, Options Outstanding	$ 23.19
Number Exercisable, Options Exercisable	265,438
Weighted-Average Exercise Price, Options Exercisable	$ 23.19
26.06
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Upper limit	$ 26.06
Number Outstanding, Options Outstanding	574,343
Weighted-Average Remaining Contractual Life, Options Outstanding	2 years 0 months 4 days
Weighted-Average Exercise Price, Options Outstanding	$ 26.06
Number Exercisable, Options Exercisable	574,343
Weighted-Average Exercise Price, Options Exercisable	$ 26.06
26.52 to 27.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Lower limit	$ 26.52
Exercise price range, Upper limit	$ 27.58
Number Outstanding, Options Outstanding	74,800
Weighted-Average Remaining Contractual Life, Options Outstanding	2 years 4 months 24 days
Weighted-Average Exercise Price, Options Outstanding	$ 27.26
Number Exercisable, Options Exercisable	74,800
Weighted-Average Exercise Price, Options Exercisable	$ 27.26
27.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, Upper limit	$ 27.60
Number Outstanding, Options Outstanding	9,336
Weighted-Average Remaining Contractual Life, Options Outstanding	2 years 4 months 17 days
Weighted-Average Exercise Price, Options Outstanding	$ 27.60
Number Exercisable, Options Exercisable	9,336
Weighted-Average Exercise Price, Options Exercisable	$ 27.60

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

-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

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

-Subparagraph (e)(1)

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

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- Definition

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

-Subparagraph (g)

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

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