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Share Repurchases - Additional Information (Detail) $ / shares in Units, shares in Millions	1 Months Ended					3 Months Ended
	Apr. 28, 2016 $ / shares shares	Mar. 31, 2016 USD ($) Arrangements $ / shares shares	Feb. 29, 2016 $ / shares shares	Jan. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Mar. 31, 2016 USD ($) Arrangements $ / shares
Accelerated Share Repurchases [Line Items]
Common stock repurchases						$ 250,000,000
Cash paid for repurchase of common stock						250,000,000
Authorization of future share repurchase		$ 900,000,000				$ 900,000,000
Number of ASRs completed | Arrangements		2				2
Accelerated Share Repurchase Agreement (ASR) [Member]
Accelerated Share Repurchases [Line Items]
Common stock repurchases		$ 100,000,000			$ 150,000,000
Shares of common stock received under ASR | shares		1.2	0.9	2.0
Cash paid for repurchase of common stock		$ 100,000,000		$ 150,000,000
Accelerated share repurchase, price per share | $ / shares		$ 56.95		$ 53.37		$ 56.95
Accelerated Share Repurchase Agreement (ASR) [Member] | Weighted Average [Member]
Accelerated Share Repurchases [Line Items]
Final weighted average per share purchase price during the repurchase period | $ / shares			$ 53.15
Accelerated Share Repurchase Agreement (ASR) [Member] | Subsequent Event [Member]
Accelerated Share Repurchases [Line Items]
Shares of common stock received under ASR | shares	0.5
Accelerated Share Repurchase Agreement (ASR) [Member] | Subsequent Event [Member] | Weighted Average [Member]
Accelerated Share Repurchases [Line Items]
Final weighted average per share purchase price during the repurchase period | $ / shares	$ 58.33

X

- 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

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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=56944662&loc=d3e3291-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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- Definition

Amount remaining of a stock repurchase plan authorized.

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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 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30
-Article 5

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-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

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Number of accelerated share repurchase agreement completed.

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