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Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2018 | Sep. 30, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | May 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Number of shares available for grant |  |  | 2,400 |  |  |
Maximum contribution allowed under employee stock purchase plan as % of employee's earnings |  |  | 15.00% |  |  |
Total number of shares purchased under employee stock purchase plan |  |  | 1,400 |  |  |
Plan period employee stock purchase plan, in months |  |  | 3 months |  |  |
Purchase price calculation for shares of stock under employee stock purchase plan |  |  | The purchase price for each share of stock is the lesser of 90% of the market price on the first day of the plan period or 100% of the market price on the last day of the plan period. |  |  |
Incremental stock-based compensation cost due to acceleration of awards | $ 1 | $ 4 | $ 1 | $ 4 | $ 7 |
Total intrinsic value of options exercised in the period |  |  | 44 | 76 | 53 |
Proceeds from stock plans |  |  | 45 | $ 91 | $ 56 |
Intrinsic value of options outstanding |  |  | $ 86 |  |  |
Number of options exercisable |  |  | 794 | 900 | 1,300 |
Weighted-average exercise price of exercisable options |  |  | $ 117.08 | $ 103.63 | $ 92.26 |
Weighted-average remaining contractual term of options exercisable |  |  | 5 years 9 months 18 days |  |  |
Number of options outstanding which are vested and expected to vest |  |  | 1,800 |  |  |
Aggregate intrinsic value of outstanding options which are vested and expect to vest |  |  | $ 86 |  |  |
Weighted-average exercise price of outstanding options which are vested and expected to vest |  |  | $ 142.18 |  |  |
Weighted-average remaining contractual term of outstanding options which are vested and expected to vest |  |  | 7 years 1 month 6 days |  |  |
Unrecognized compensation costs on unvested options |  |  | $ 41 |  |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Award vesting period |  |  | 5 years |  |  |
Stock-based compensation costs |  |  | $ 16 | $ 17 | $ 17 |
Weighted-average period of recognition for unrecognized compensation costs on nonvested awards |  |  | 3 years 2 months 12 days |  |  |
Shares granted |  |  | 91 |  |  |
Weighted-average grant date fair value of shares granted |  |  | $ 207.85 |  |  |
Unvested shares at end of period |  |  | 304 | 374 |  |
Unrecognized compensation costs on unvested awards |  |  | $ 32 |  |  |
Performance Stock Unit Plan [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Stock-based compensation costs |  |  | $ 5 |  |  |
Weighted-average period of recognition for unrecognized compensation costs on nonvested awards |  |  | 2 years 3 months 18 days |  |  |
Shares granted |  |  | 40 | 40 | 27 |
Weighted-average grant date fair value of shares granted |  |  | $ 235.63 |  |  |
Unvested shares at end of period |  |  | 100 | 64 |  |
Unrecognized compensation costs on unvested awards |  |  | $ 14 |  |  |
Stock-based compensation costs, less than $1 million |  |  |  | Less than $1 million |  |
Performance Stock Unit Plan [Member] | Minimum [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Award vesting rights |  |  | 0.00% |  |  |
Performance Stock Unit Plan [Member] | Maximum [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Award vesting rights |  |  | 200.00% |  |  |
Restricted Stock [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Stock-based compensation costs |  |  | $ 1 | $ 1 | $ 1 |
Shares granted |  |  | 5 | 8 | 10 |
Weighted-average grant date fair value of shares granted |  |  | $ 194.73 | $ 130.35 | $ 113.88 |
Unvested shares at end of period |  |  | 5 |  |  |
Employee Stock [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Stock-based compensation costs |  |  | $ 1 | $ 1 | $ 1 |
Employee Stock [Member] | Employee Stock Purchase Plan Of 2009 [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Number of shares authorized under plan |  |  |  |  |  | 900
Equity Option [Member] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Award vesting period |  |  | 5 years |  |  |
Award expiration period |  |  | 10 years |  |  |
Weighted-average period of recognition for unrecognized compensation costs on nonvested awards |  |  | 3 years 6 months |  |  |

X
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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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
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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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
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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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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