Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)				1 Months Ended		3 Months Ended		6 Months Ended
	Sep. 15, 2020	Jun. 11, 2020	May 15, 2020	Jun. 30, 2021	Oct. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Mar. 31, 2020
Accounting Policies [Line Items]
Other comprehensive income (loss)						$ 0	$ 0	$ 0	$ 0
Cash deposits included in restricted cash				$ 37,116,000		$ 37,116,000		$ 37,116,000		$ 33,826,000
Proceeds from issuance of common stock, net of underwriting discount and before deducting offering expenses									504,023,000
Stock offering expenses	$ 1,500,000
Proceeds from issuance of common stock	$ 569,500,000
Common stock, issued	10,800,000
Sale of stock, price per share	$ 54.50
ASU 2019-12
Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]				true		true		true
Change in accounting principle, accounting standards update, adoption date				Jan. 01, 2021		Jan. 01, 2021		Jan. 01, 2021
Change in accounting principle, accounting standards update, immaterial effect [true false]				true		true		true
ASU 2020-06
Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]				true		true		true
Change in accounting principle, accounting standards update, adoption date				Jan. 01, 2021		Jan. 01, 2021		Jan. 01, 2021
Change in accounting principle, accounting standards update, immaterial effect [true false]				true		true		true
Change in accounting principle, accounting standards update, early adoption [true false]				true		true		true
RA Agreement
Accounting Policies [Line Items]
Common stock, issued			183,870
Term for issuance of additional shares of common stock			4 years
Sale of stock, price per share			$ 11.57
0.75% Unsecured Convertible Senior Notes Due 2026
Accounting Policies [Line Items]
Debt instrument aggregate principal amount				$ 625,000,000.0		$ 625,000,000.0		$ 625,000,000.0
Debt instrument interest rate				0.75%		0.75%		0.75%
Debt instrument maturity year				2026
Initial Public Offering
Accounting Policies [Line Items]
Proceeds from issuance of common stock, net of underwriting discount and before deducting offering expenses		$ 504,000,000.0
Stock offering expenses		$ 7,500,000
Common stock, issued		24,437,500
Sale of stock, price per share		$ 22.00
Selling, General and Administrative Expenses
Accounting Policies [Line Items]
Advertising expense						$ 23,500,000	11,600,000	$ 53,100,000	29,500,000
Selling, General and Administrative Expenses | Shipping and Handling
Accounting Policies [Line Items]
Shipping and handling expenses						20,200,000	$ 5,500,000	$ 35,300,000	$ 11,300,000
Maximum
Accounting Policies [Line Items]
Business combination, measurement period								1 year
Maximum | RA Agreement
Accounting Policies [Line Items]
Issuance of additional shares of common stock			8,641,914
Vehicle Floorplan Facilities | Line Of Credit
Accounting Policies [Line Items]
Increased borrowing capacity											$ 450,000,000.0
Amended to extend maturity date					2022-09
Vehicle Floorplan Facilities | Cash Deposits
Accounting Policies [Line Items]
Cash deposits included in restricted cash				$ 35,300,000		$ 35,300,000		$ 35,300,000		$ 31,600,000