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Equity-Based Compensation - Exercise price (Detail)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable shares, end of year | shares	2,269
Exercisable, weighted average per share exercise price	$ 46.86
Weighted average remaining years	4 years 10 months 24 days
$33.49-$50.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, low end of range	$ 33.49
Exercise price, high end of range	$ 50.00
Exercisable shares, end of year | shares	1,288
Exercisable, weighted average per share exercise price	$ 37.89
Weighted average remaining years	3 years 6 months
$50.01-$70.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, low end of range	$ 50.01
Exercise price, high end of range	$ 70.00
Exercisable shares, end of year | shares	797
Exercisable, weighted average per share exercise price	$ 55.20
Weighted average remaining years	6 years 6 months
$70.01-$85.34 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, low end of range	$ 70.01
Exercise price, high end of range	$ 85.34
Exercisable shares, end of year | shares	184
Exercisable, weighted average per share exercise price	$ 73.40
Weighted average remaining years	8 years 2 months 12 days

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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=96867065&loc=d3e5070-113901

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