Stock Compensation Plans - SSAR's and Stock Option Outstanding (Detail) (SSAR's and Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	151
Weighted Average Exercise Price	$ 51.13
Aggregate Intrinsic Value	$ 7,490
$26 - $30 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	1
Price Range, lower limit	$ 26
Price Range, upper limit	$ 30
Weighted Average Remaining Contractual Life (in years)	4 years 4 months 24 days
Weighted Average Exercise Price	$ 30.48
$31 - $35 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	18
Price Range, lower limit	$ 31
Price Range, upper limit	$ 35
Weighted Average Remaining Contractual Life (in years)	10 months 21 days
Weighted Average Exercise Price	$ 35.03
$36 - $40 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	6
Price Range, lower limit	$ 36
Price Range, upper limit	$ 40
Weighted Average Remaining Contractual Life (in years)	1 year 4 months 6 days
Weighted Average Exercise Price	$ 36.00
$41 - $50 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	39
Price Range, lower limit	$ 41
Price Range, upper limit	$ 50
Weighted Average Remaining Contractual Life (in years)	1 year 10 months 17 days
Weighted Average Exercise Price	$ 44.56
$51 - $60 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	59
Price Range, lower limit	$ 51
Price Range, upper limit	$ 60
Weighted Average Remaining Contractual Life (in years)	3 years 4 months 24 days
Weighted Average Exercise Price	$ 56.68
$61 - $65 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	28
Price Range, lower limit	$ 61
Price Range, upper limit	$ 65
Weighted Average Remaining Contractual Life (in years)	1 year 7 months 10 days
Weighted Average Exercise Price	$ 62.13

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ 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

+ Details

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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 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

+ Details

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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

+ Details

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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

+ Details

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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

+ Details

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