Stock-Based Compensation - Summary of 2009 ESPP (Details) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average per share discount from market value for shares purchased (in dollars per share)	$ 17.83	$ 13.10	$ 15.20
The 2009 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased pursuant to 2009 ESPP	112,138
Weighted average per share price of shares purchased (in dollars per share)	$ 101.03
Weighted average per share discount from market value for shares purchased (in dollars per share)	$ 17.83
Shares available for purchase pursuant to 2009 ESPP	1,526,505

The weighted average discount per share for compensation expense recognized under the 2009 ESPP.

No definition available.

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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 difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

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- Definition

Per share weighted-average price paid for shares purchased on open market for issuance under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901

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- Definition

Number of shares issued under share-based payment arrangement.

+ References

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