Summary of Significant Accounting Policies - Additional Information (Detail)			12 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2019 USD ($) Segment $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)	Nov. 30, 2018 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Number of operating segments | Segment			1
Interest costs incurred			$ 1,600,000	$ 1,600,000	$ 1,700,000
Interest costs capitalized			600,000	800,000	800,000
Total capitalized payroll costs related to internal use software projects			30,400,000	22,000,000.0
Amortization expense of capitalized software costs			19,000,000.0	12,500,000	7,000,000.0
Goodwill impairment amount	$ 0	$ 0	0	0	0
Impairment of intangible assets with definite lives			0	0	0
Impairment of long-lived assets			$ 0	0	0
Deferred revenue expect to recognize description			We expect to recognize $11.1 million of deferred revenue related to material right performance obligations in 2020, $11.0 million in 2021, and $54.1 million of such deferred revenue thereafter.
Advertising costs			$ 25,900,000	16,800,000	7,900,000
Sales taxes			8,300,000	$ 6,500,000	$ 5,000,000.0
Stock Repurchase Plan [Member]
Summary Of Significant Accounting Policy [Line Items]
Available authorized repurchase amount			$ 119,400,000
Stock repurchase plan expiration date			Nov. 19, 2020
Number of common stocks repurchased during the period | shares			219,764,000	1,108,885,000
Stock repurchased, average costs per share | $ / shares			$ 193.51	$ 113.12
Stock Repurchase Plan [Member] | Restricted Stock [Member]
Summary Of Significant Accounting Policy [Line Items]
Shares withheld to satisfy tax withholding obligations | shares				186,165
Maximum [Member] | Stock Repurchase Plan [Member]
Summary Of Significant Accounting Policy [Line Items]
Stock repurchase plan, authorized amount						$ 150,000,000.0
Internal use Software [Member]
Summary Of Significant Accounting Policy [Line Items]
Capitalized and amortized period			3 years