Financial Instruments and Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of Financial Instruments by Significant Categories and Fair Value Measurement on a Recurring Basis

The following table summarizes our financial instruments by significant categories and fair value measurement on a recurring basis as of March 31, 2019 and December 31, 2018.

(in millions)	Level 1		Level 2		Total
March 31, 2019
Cash equivalents:
Money market mutual funds	$	74	$	—	74
U.S. treasuries	—		3		3
Total cash equivalents	74		3		77
Investments:
Asset-backed securities	—		35		35
Corporate bonds	—		100		100
U.S. government agencies and government-sponsored agencies	—		6		6
U.S. treasuries	—		42		42
Other debt securities	—		6		6
Total investments	—		189		189
Restricted cash equivalents:
Money market mutual funds	42		—		42
Commercial paper	19		—		19
Total restricted cash equivalents	61		—		61
Restricted investments:
U.S. treasuries	—		5		5
Exchange traded fund	1		—		1
Certificate of deposit	—		2		2
Total restricted investments	1		7		8
Total unrestricted and restricted cash equivalents and investments	$	136	$	199	$	335

(in millions)	Level 1		Level 2		Total
December 31, 2018
Cash equivalents
Money market mutual funds	$	4	$	—	$	4
U.S. treasuries	—		1		1
Total cash equivalents	4		1		5
Investments
Asset-backed securities	—		33		33
Corporate bonds	—		99		99
U.S. government agencies and government-sponsored agencies	—		7		7
U.S. treasuries	—		41		41
Other debt securities	—		9		9
Total investments	—		189		189
Restricted cash equivalents:
Money market mutual funds	48		—		48
Commercial paper	20		—		20
Total restricted cash equivalents	68		—		68
Restricted investments:
U.S. treasuries	—		5		5
Exchange traded fund	1		—		1
Certificate of deposit	—		2		2
Total restricted investments	1		7		8
Total unrestricted and restricted cash equivalents and investments	$	73	$	197	$	270