Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) billing_cycle	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 50,847,000	$ 0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Amount	5,000,000	16,000,000	$ 11,000,000
Sales and marketing	363,111,000	311,433,000	313,251,000
Engineering and development	$ 69,460,000	52,139,000	29,630,000
Maximum original maturity term of investments to be considered cash and cash equivalents	3 months
Number of unsuccessful billing cycles before account termination | billing_cycle	3
Restricted cash	$ 2,015,000	2,047,000
Effective income tax rate reconciliation, change in enacted tax rate, amount	69,378,000
Foreign currency transaction gain (loss), before tax	727,000	145,000	620,000
Net cash used in investing activities	(52,079,000)	(407,230,000)	(30,737,000)
Effect of exchange rate changes on cash and cash equivalents	(395,000)	(410,000)	1,319,000
Cash and cash equivalents	23,620,000	5,057,000	31,360,000		$ 29,078,000
Cash, cash equivalents, and restricted cash, beginning of period	25,635,000	7,104,000	33,327,000		$ 30,929,000
Net cash provided by operating activities	92,926,000	123,205,000	128,058,000
Advertising Expense	46,606,000	54,735,000	$ 57,703,000
Operating Lease, Liability	$ 58,199,000
Customer premise equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life of property and equipment	3 years
Maximum | Network equipment and computer hardware
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life of property and equipment	5 years
Minimum | Network equipment and computer hardware
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life of property and equipment	3 years
Purchased Intangible Assets | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible asset useful life	12 years
Purchased Intangible Assets | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible asset useful life	2 years
Letter of credit-lease deposits
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 1,528,000	$ 1,516,000
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset				$ 57,300,000
Operating Lease, Liability				64,500,000
Adjustment | Retained Earnings | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 458,000