Share-Based Compensation - Schedule of Restricted Stock Units Activity (Detail) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock Units and Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and PSUs Outstanding, Beginning Balance	7,287	8,413	8,676
RSUs and PSUs, Granted	2,788	2,628	3,105
RSUs and PSUs, Vested	(2,254)	(3,112)	(2,881)
RSUs and PSUs, Cancelled	(567)	(642)	(487)
RSUs and PSUs Outstanding, Ending Balance	7,254	7,287	8,413
Weighted Average Grant Date Fair Value, RSUs and PSUs, Beginning balance	$ 61.21	$ 51.15	$ 39.89
Weighted Average Grant Date Fair Value, RSUs and PSUs, Granted	81.90	69.95	69.43
Weighted Average Grant Date Fair Value, RSUs and PSUs, Vested	51.20	41.71	37.61
Weighted Average Grant Date Fair Value, RSUs and PSUs, Cancelled	64.06	59.66	47.26
Weighted Average Grant Date Fair Value, RSUs and PSUs, Ending balance	$ 72.05	$ 61.21	$ 51.15
Restricted Stock Units and Performance Stock Units [Member] \| Time Based Stock Options and SARs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and PSUs Outstanding, Beginning Balance	4,111	5,302	5,895
RSUs and PSUs, Granted	1,484	1,450	1,694
RSUs and PSUs, Vested	(1,824)	(2,242)	(1,953)
RSUs and PSUs, Cancelled	(306)	(399)	(334)
RSUs and PSUs Outstanding, Ending Balance	3,465	4,111	5,302
Restricted Stock Units and Performance Stock Units [Member] \| Performance Based Stock Options and RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and PSUs Outstanding, Beginning Balance	790	1,740	2,781
RSUs and PSUs, Vested	(430)	(870)	(928)
RSUs and PSUs, Cancelled	(133)	(80)	(113)
RSUs and PSUs Outstanding, Ending Balance	227	790	1,740
Performance Shares PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and PSUs Outstanding, Beginning Balance	2,386	1,371
RSUs and PSUs, Granted	1,304	1,178	1,411
RSUs and PSUs, Cancelled	(128)	(163)	(40)
RSUs and PSUs Outstanding, Ending Balance	3,562	2,386	1,371

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ 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)(2)(iii)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ 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)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ 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)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ 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)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ 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)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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