Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Summary of Financial Instruments Measured at Fair Value on Recurring Basis

The following tables set forth the Company’s financial instruments that were measured at fair value on a recurring basis as of the dates indicated by level within the fair value hierarchy (in thousands):

	June 30, 2019
	Level 1		Level 2		Level 3		Total
Unrestricted Balances(1)
Money market funds	$	67,232	$	—	$	—	$	67,232
Certificates of deposit		—		1,488,456		—		1,488,456
Commercial paper		—		1,025,765		—		1,025,765
Corporate bonds		—		284,677		—		284,677
Total unrestricted cash equivalents and short-term investments		67,232		2,798,898		—		2,866,130
Restricted Balances(2)(3)
Money market funds		1,438		—		—		1,438
Certificates of deposit		—		434,463		—		434,463
Commercial paper		—		734,380		—		734,380
Corporate bonds		—		62,531		—		62,531
Total restricted cash equivalents and investments		1,438		1,231,374		—		1,232,812
Total unrestricted and restricted cash equivalents and investments	$	68,670	$	4,030,272	$	—	$	4,098,942

(1) Included in cash and cash equivalents and short-term investments in the Company’s condensed consolidated balance sheet as of June 30, 2019 in addition to $339.2 million of cash and $105.0 million of a term deposit.

(2) Included in restricted cash and cash equivalents and restricted investments in the Company’s condensed consolidated balance sheet as of June 30, 2019 in addition to $57.6 million of restricted cash.

(3) Included in prepaid expenses and other current assets in the Company’s condensed consolidated balance sheet as of June 30, 2019 is $2.1 million of restricted cash.

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Unrestricted Balances(1)
Money market funds	$	38,528	$	—	$	—	$	38,528
Certificates of deposit		—		497,554		—		497,554
Commercial paper		—		1,134,721		—		1,134,721
Corporate bonds		—		119,039		—		119,039
Total unrestricted cash equivalents and short-term investments		38,528		1,751,314		—		1,789,842
Restricted Balances(2)(3)
Money market funds		4,620		—		—		4,620
Certificates of deposit		—		307,604		—		307,604
Commercial paper		—		624,509		—		624,509
Corporate bonds		—		65,586		—		65,586
Total restricted cash equivalents and investments		4,620		997,699		—		1,002,319
Total unrestricted and restricted cash equivalents and investments	$	43,148	$	2,749,013	$	—	$	2,792,161

(1) Included in cash and cash equivalents and short-term investments in the Company’s condensed consolidated balance sheet as of December 31, 2018 in addition to $248.0 million of cash.

(2) Included in restricted cash and cash equivalents and restricted investments in the Company’s condensed consolidated balance sheet as of December 31, 2018 in addition to $50.2 million of restricted cash.

(3) Included in prepaid expenses and other current assets in the Company’s condensed consolidated balance sheet as of December 31, 2018 is $1.4 million of restricted cash.