Cash and Cash Equivalents, Investments and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2021

Cash and Cash Equivalents [Abstract]

Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Market Value of Cash and Cash Equivalents and Available-for-Sale Investments

The following tables present the amortized cost, gross unrealized gains and losses and estimated fair market value of our cash and cash equivalents, investments, including beneficial interests in securitizations, and restricted cash as of the dates presented (in thousands):

	December 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Market Value
Cash	$	479,110	$	—	$	—	$	479,110
Cash equivalents:
Money market funds	2,132,389		—		—		2,132,389
Short-term investments:
U.S. government agency securities	472,570		—		(1,719)		470,851
Corporate bonds	33,172		3		(95)		33,080
Commercial paper	9,991		—		—		9,991
Restricted cash	226,651		—		—		226,651
Beneficial interests in securitizations	66,167		8,936		—		75,103
Total	$	3,420,050	$	8,939	$	(1,814)	$	3,427,175

	December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Market Value
Cash	$	213,518	$	—	$	—	$	213,518
Cash equivalents:
Money market funds	1,486,384		—		—		1,486,384
Municipal securities	3,229		—		(1)		3,228
Short-term investments:
Treasury bills	1,163,748		65		—		1,163,813
U.S. government agency securities	1,037,572		57		(52)		1,037,577
Municipal securities	16,226		—		(6)		16,220
Certificates of deposit	498		—		—		498
Restricted cash	75,805		—		—		75,805
Total	$	3,996,980	$	122	$	(59)	$	3,997,043