Employee Stock Purchase Plan [Abstract]

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- Definition

Stock Repurchase Program, Increase (Decrease) in Authorized Amount

+ References

No definition available.

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- Definition

Number of shares to be repurchased in accordance with a policy to use treasury stock to satisfy share-award conversions.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

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

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-Publisher FASB
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- Definition

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.

+ References

No definition available.

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- Definition

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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-Publisher FASB
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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

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- Definition

Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Stockholders' Equity - Narrative (Details) - USD ($)	3 Months Ended					9 Months Ended
Stockholders' Equity - Narrative (Details) - USD ($)	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 11, 2019	Jan. 23, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options that are exercisable (shares)	1,400,000					1,400,000
Outstanding options that are exercisable, weighted average exercise price (USD per share)	$ 59.49					$ 59.49
Employee Stock Purchase Plan
Stock repurchased during period	$ 181,188,000	$ 33,717,000	$ 151,585,000	$ 50,832,000	$ 1,895,000	$ 366,500,000
Authorized stock repurchase amount							$ 200,000,000.0	$ 500,000,000.0	$ 350,000,000.0
Period in force of stock repurchase program						3 years	3 years
Increase in authorized stock repurchase amount									$ 150,000,000.0
Remaining authorized stock repurchase amount	$ 408,700,000					$ 408,700,000
Employee Stock Purchase Plan
Employee Stock Purchase Plan
Share purchase price as percent of market price (as a percent)						85.00%
Shares available for future purchases (shares)						60,642