Income Taxes - Additional Information (Detail) - USD ($)			3 Months Ended
	Mar. 11, 2015	Nov. 20, 2014	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Feb. 09, 2016
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits that would impact effective tax rate			$ 0	$ 0
Increase (decrease) in valuation allowance					$ (73,600,000)
Income tax expense (benefit)			5,774,000		(99,902,000)
Deferred federal and state deferred tax expense (benefit)			3,700,000		(29,000,000)
Federal and state current income taxes			1,400,000		2,200,000
Deferred foreign income tax expense (benefit)			(200,000)		(700,000)
Provision for foreign tax			900,000		1,100,000
Amount of net operating loss carry-forwards available to offset future U.S. federal taxable income				142,700,000
Amount of net operating loss carry-forwards available to offset future state taxable income				125,600,000
Loss carry-forwards available to future foreign taxable income				$ 96,800,000
Net operating loss carry-forwards annual limitations			$ 77,100,000
Common stock, shares issued (in shares)			135,789,327	134,793,857
Constant Contact, Inc.
Operating Loss Carryforwards [Line Items]
Increase (decrease) in valuation allowance					(73,600,000)
Follow-On Public Offering
Operating Loss Carryforwards [Line Items]
Common stock, shares issued (in shares)		13,000,000
Number of shares sold by the selling stockholders	12,000,000
Common stock, per share	$ 19.00
Over-Allotment Option
Operating Loss Carryforwards [Line Items]
Number of shares sold by the selling stockholders	1,800,000	1,950,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Deferred tax assets, capital loss carryforwards				$ 3,400,000
Tax credit carryforward				20,300,000
Domestic Tax Authority | Constant Contact, Inc.
Operating Loss Carryforwards [Line Items]
Tax credit carryforward						$ 10,900,000
NOL carry-forward						60,200,000
Federal And State
Operating Loss Carryforwards [Line Items]
Increase (decrease) in valuation allowance			$ 14,500,000	10,000,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Deferred tax assets, capital loss carryforwards				1,400,000
Tax credit carryforward				12,200,000
State and Local Jurisdiction | Constant Contact, Inc.
Operating Loss Carryforwards [Line Items]
Tax credit carryforward						9,200,000
NOL carry-forward						$ 32,400,000
India
Operating Loss Carryforwards [Line Items]
Loss carry-forwards available to future foreign taxable income				2,500,000
CHINA
Operating Loss Carryforwards [Line Items]
Loss carry-forwards available to future foreign taxable income				300,000
NETHERLANDS
Operating Loss Carryforwards [Line Items]
Loss carry-forwards available to future foreign taxable income				10,700,000
United Kingdom
Operating Loss Carryforwards [Line Items]
Loss carry-forwards available to future foreign taxable income				81,100,000
ISRAEL
Operating Loss Carryforwards [Line Items]
Loss carry-forwards available to future foreign taxable income				1,900,000
SINGAPORE
Operating Loss Carryforwards [Line Items]
Loss carry-forwards available to future foreign taxable income				$ 300,000
Research Tax Credit Carryforward | Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Increase (decrease) in valuation allowance					$ 7,300,000