Share-based Compensation Plans - Stock Options and SARs Outstanding and Exercisable (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012
$21.15 - $28.46 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Minimum	$ 21.15
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Maximum	$ 28.46
Range of Exercise Prices, Options, Exercisable, Exercise Price, Minimum	$ 21.15
Range of Exercise Prices, Options, Exercisable, Exercise Price, Maximum	$ 28.46
$28.48 - $32.94 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Minimum	$ 28.48
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Maximum	$ 32.94
Range of Exercise Prices, Options, Exercisable, Exercise Price, Minimum	$ 28.48
Range of Exercise Prices, Options, Exercisable, Exercise Price, Maximum	$ 32.94
$33.14 - $43.83 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Minimum	$ 33.14
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Maximum	$ 43.83
Range of Exercise Prices, Options, Exercisable, Exercise Price, Minimum	$ 33.14
Range of Exercise Prices, Options, Exercisable, Exercise Price, Maximum	$ 43.83
$21.15 - $43.83 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Minimum	$ 21.15
Range of Exercise Prices, Vested and Expected to Vest, Exercise Price, Maximum	$ 43.83
Range of Exercise Prices, Options, Exercisable, Exercise Price, Minimum	$ 21.15
Range of Exercise Prices, Options, Exercisable, Exercise Price, Maximum	$ 43.83
Stock Options and SARs [Member] \| $21.15 - $28.46 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested and Expected to Vest, Number Outstanding	1,483,520
Options, Vested and Expected to Vest, Weighted-average Remaining Contractual Life	2 years 2 months 12 days
Options, Vested and Expected to Vest, Weighted-average Exercise Price	$ 24.76
Options, Vested and Expected to Vest, Aggregate Intrinsic Value	$ 7,373
Options, Number Exercisable	1,483,520
Options, Weighted-average Remaining Contractual Life	2 years 2 months 12 days
Options, Weighted-average Exercise Price	$ 24.76
Options, Aggregate Intrinsic Value	7,373
Stock Options and SARs [Member] \| $28.48 - $32.94 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested and Expected to Vest, Number Outstanding	1,861,060
Options, Vested and Expected to Vest, Weighted-average Remaining Contractual Life	4 years 3 months 18 days
Options, Vested and Expected to Vest, Weighted-average Exercise Price	$ 30.42
Options, Vested and Expected to Vest, Aggregate Intrinsic Value	986
Options, Number Exercisable	1,134,550
Options, Weighted-average Remaining Contractual Life	3 years 2 months 12 days
Options, Weighted-average Exercise Price	$ 28.87
Options, Aggregate Intrinsic Value	986
Stock Options and SARs [Member] \| $33.14 - $43.83 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested and Expected to Vest, Number Outstanding	1,706,160
Options, Vested and Expected to Vest, Weighted-average Remaining Contractual Life	2 years 2 months 12 days
Options, Vested and Expected to Vest, Weighted-average Exercise Price	$ 35.96
Options, Number Exercisable	1,706,160
Options, Weighted-average Remaining Contractual Life	2 years 2 months 12 days
Options, Weighted-average Exercise Price	$ 35.96
Stock Options and SARs [Member] \| $21.15 - $43.83 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Vested and Expected to Vest, Number Outstanding	5,050,740
Options, Vested and Expected to Vest, Weighted-average Remaining Contractual Life	3 years
Options, Vested and Expected to Vest, Weighted-average Exercise Price	$ 30.63
Options, Vested and Expected to Vest, Aggregate Intrinsic Value	8,359
Options, Number Exercisable	4,324,230
Options, Weighted-average Remaining Contractual Life	2 years 6 months
Options, Weighted-average Exercise Price	$ 30.26
Options, Aggregate Intrinsic Value	$ 8,359

Share based compensation arrangement by share based payment award options exercisable exercise price maximum.

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- Definition

Share based compensation arrangement by share based payment award options exercisable exercise price minimum.

+ References

No definition available.

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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

+ 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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- Definition

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

+ 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)(iii)

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c), d(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ 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)(iii)

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

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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

+ References

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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest 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

-Subparagraph (e)(1)

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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

+ References

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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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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 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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