Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

Financial instruments measured and recorded at fair value on a recurring basis as of March 31, 2021 and December 31, 2020 are classified based on the valuation technique level in the tables below (in thousands):

	March 31, 2021
	Total		Level 1		Level 2
Assets:
Cash equivalents:
Money market funds	$	532,493	$	532,493	$	—
Commercial paper	99,276		—		99,276
Short-term investments:
Commercial paper	605,364		—		605,364
Corporate debt securities	610,580		—		610,580
Long-term investments:
Corporate debt securities	672,226		—		672,226
Agency bonds	38,998		—		38,998
Total assets measured and recorded at fair value	$	2,558,937	$	532,493	$	2,026,444

	December 31, 2020
	Total		Level 1		Level 2
Assets:
Cash equivalents:
Money market funds	$	464,799	$	464,799	$	—
Short-term investments:
Commercial paper	204,170		—		204,170
Corporate debt securities	461,397		—		461,397
Long-term investments:
Corporate debt securities	484,597		—		484,597
Agency bonds	39,031		—		39,031
Total assets measured and recorded at fair value	$	1,653,994	$	464,799	$	1,189,195

Fair Value Measurements, Nonrecurring

The carrying amounts and estimated fair values of the notes as of March 31, 2021 and December 31, 2020 are as follows (in thousands):

	March 31, 2021				December 31, 2020 (1)
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
2026 notes	$	985,706	$	1,054,020	$	761,930	$	1,129,370
2025 notes	688,240		1,202,129		640,614		1,456,800
2023 notes	109,494		377,186		104,378		376,949
Convertible senior notes, net	$	1,783,440	$	2,633,335	$	1,506,922	$	2,963,119

(1) Prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method. Refer to Note 7, “Convertible Senior Notes” for more information.