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Share-Based Compensation Share-Based Compensation - Schedule of Fair Value Options Granted and Assumptions (Details) - Stock Options - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

Mar. 31, 2016

Mar. 31, 2015

Share-based Compensation

Stock options granted, fair value

$ 16.0

$ 0.5

Stock options, expiration period (in years)

7 years

Stock options granted, estimated fair value

$ 38.90

$ 53.59

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]

Dividend yield

0.00%

0.00%

Expected volatility

^[1]

30.60%

27.90%

Risk-fee interest rate

^[2]

1.60%

1.40%

Expected life of options (in years)

^[3]

5 years 8 months 12 days

5 years

Forfeiture rate

0.00%

0.00%

Minimum

Share-based Compensation

Stock options, vesting period (in years)

3 years

Maximum

Share-based Compensation

Stock options, vesting period (in years)

4 years

[1]	Expected volatility is based on historical and implied volatility.
[2]	Risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date of the grant.
[3]	Expected life of options (in years) is based on the Company’s historical data and expected exercise behavior.

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- Definition

Represents the expected rate the entity will cancel the stock option awards due to nonfulfillment of certain conditions of equity-based compensation arrangements.

+ References

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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-Publisher FASB
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-SubTopic 10
-Section 50
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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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