Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($) FinancialInstitution	Dec. 31, 2018 USD ($) FinancialInstitution	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Unrealized loss on short-term investments		$ 17,000	$ (17,000)	$ 0
Foreign currency gains (loss)		(200,000)	(500,000)	100,000
Impairment of property and equipment			400,000	0
Impairment to operating right of use assets		900,000
Short-term investments		0	42,146,000
Content related expenses		1,700,000
Advertising costs		7,300,000	$ 3,000,000.0	3,400,000
Operating lease right-of-use assets	$ 39,900,000	283,291,000
Operating lease liability	42,100,000	$ 319,590,000
Reclassification of deferred and prepaid rents to right of use assets	$ 2,200,000
Maximum
Summary Of Significant Accounting Policies [Line Items]
Business combination measurement period from acquisition		1 year
Cash equivalents maturity period		90 days
Property and equipment, estimated useful lives		5 years
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		18 months
Customer 1
Summary Of Significant Accounting Policies [Line Items]
Number of financial institutions which manage cash balances | FinancialInstitution		1	1
Customer 2
Summary Of Significant Accounting Policies [Line Items]
Number of financial institutions which manage cash balances | FinancialInstitution		1
Cash, Cash Equivalents and Short-term Investment | Customer 1
Summary Of Significant Accounting Policies [Line Items]
Percentage of cash, cash equivalents balances		65.00%	97.00%
Cash, Cash Equivalents and Short-term Investment | Customer 2
Summary Of Significant Accounting Policies [Line Items]
Percentage of cash, cash equivalents balances		34.00%
Website and Internal-Use Software
Summary Of Significant Accounting Policies [Line Items]
Capitalized costs		$ 100,000	$ 1,000,000.0	2,600,000
Amortized expenses		$ 1,600,000	$ 2,000,000.0	$ 1,100,000
Estimated useful life		2 years
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives description		shorter of the lease term or their estimated useful lives, which range from five to ten years
Leasehold Improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		10 years
Leasehold Improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		5 years