Stock-Based Compensation - Summary of Restricted Stock Awards and Restricted Stock Units (Detail)	12 Months Ended
Dec. 31, 2019 $ / shares shares
Restricted Stock Awards and Units \| Constant Contact 2011 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested, beginning balance (in shares) \| shares	868,026
Granted (in shares) \| shares	0
Vested (in shares) \| shares	(435,919)
Canceled (in shares) \| shares	(111,965)
Non-vested, ending balance (in shares) \| shares	320,142
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, non-vested, beginning balance (in usd per share) \| $ / shares	$ 8.26
Weighted average grant date fair value, granted (in usd per share) \| $ / shares	0
Weighted average grant date fair value, vested and unissued (in usd per share) \| $ / shares	8.20
Weighted average grant date fair value, canceled (in usd per share) \| $ / shares	8.26
Weighted average grant date fair value, non-vested, ending balance (in usd per share) \| $ / shares	$ 8.35
Restricted Stock Awards and Units \| 2013 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested, beginning balance (in shares) \| shares	443,247
Granted (in shares) \| shares	0
Vested (in shares) \| shares	(246,757)
Canceled (in shares) \| shares	(36,973)
Non-vested, ending balance (in shares) \| shares	159,517
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, non-vested, beginning balance (in usd per share) \| $ / shares	$ 11.67
Weighted average grant date fair value, granted (in usd per share) \| $ / shares	0
Weighted average grant date fair value, vested and unissued (in usd per share) \| $ / shares	12.57
Weighted average grant date fair value, canceled (in usd per share) \| $ / shares	9.87
Weighted average grant date fair value, non-vested, ending balance (in usd per share) \| $ / shares	$ 10.68
Restricted Stock Units \| 2013 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested, beginning balance (in shares) \| shares	5,203,259
Granted (in shares) \| shares	7,426,877
Vested (in shares) \| shares	(2,126,221)
Canceled (in shares) \| shares	(1,498,806)
Non-vested, ending balance (in shares) \| shares	9,005,109
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, non-vested, beginning balance (in usd per share) \| $ / shares	$ 7.69
Weighted average grant date fair value, granted (in usd per share) \| $ / shares	6.62
Weighted average grant date fair value, vested and unissued (in usd per share) \| $ / shares	7.70
Weighted average grant date fair value, canceled (in usd per share) \| $ / shares	7.12
Weighted average grant date fair value, non-vested, ending balance (in usd per share) \| $ / shares	$ 6.90

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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