Name:	a_Numberofyearsofpeergroupshistoricalstockpricevolatilityusedtodeterminevolatility
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The measure of the percentage amount of share price correlation during the period with a selected group of peer companies. Pair-wise correlations with selected peers is calculated as the correlation between each pair and the sum of correlations divided by the number of pairs to produce the average correlation between each pair.

No definition available.

Name:	a_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsPeerCompanySharesPriceWiseCorrelationyRate
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The measure of the percentage amount by which a share price fluctuates during a period for peer companies - maximum range. 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.

No definition available.

Name:	a_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsPeerCompanySharesVolatilityRateRangeMaximum
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The measure of the percentage amount by which a share price fluctuates during a period for peer companies - minimum range. 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.

No definition available.

Name:	a_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsPeerCompanySharesVolatilityRateRangeMinimum
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Discount rate from fair value on purchase date that participants pay for shares.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Restrictions on equity-based instruments during the vesting period, such as the inability to transfer unvested awards, are not taken into account in estimating the fair value of the award. However, restrictions that remain in effect after an award is vested, such as the inability to transfer or hedge vested options or a prohibition on the sale of outstanding vested shares (or other type of equity) for a period of time, affect the estimate of an award's fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

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.

No definition available.