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Common Stock Repurchase Program (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 1 Months Ended | 9 Months Ended
--- | --- | ---
Aug. 31, 2017 | Jun. 30, 2017 | Feb. 28, 2017 | Nov. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Accelerated Share Repurchases [Line Items] |  |  |  |  |  |
Common stock repurchases |  |  |  |  | $ 750 |
Cash paid for repurchase of common stock |  |  |  |  | 750 | $ 500
Accelerated Share Repurchase Agreement (ASR) [Member] |  |  |  |  |  |
Accelerated Share Repurchases [Line Items] |  |  |  |  |  |
Common stock repurchases | $ 500 | $ 250 |  | $ 225 |  |
Cash paid for repurchase of common stock | $ 500 | $ 250 |  | $ 225 |  |
Shares of common stock received under ASR | 5.3 | 2.7 | 0.4 | 2.8 |  |
Additional share received under ASR | 0.7 |  |  |  |  |
ASR price (dollars per share) | $ 75.25 | $ 73.46 |  | $ 63.41 |  |
ASR final weighted price (dollars per share) | $ 74.31 |  | $ 69.43 |  |  |
Authorized share repurchases |  |  |  |  | $ 0 |

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- Definition Final price paid per share for the purchase of the targeted number of shares, determined by an average market price over a fixed period of time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 25 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6405686&loc=d3e22802-112653 + Details
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- Definition The price paid per share to immediately purchase the targeted number of shares on the date of executing the accelerated share repurchase agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 25 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6405686&loc=d3e22802-112653 + Details
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- Definition The cash outflow to reacquire common stock during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585 + Details
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- Definition Number of shares that have been repurchased during the period and are being held in treasury. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 + Details
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