Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summary of Balances of Cash Equivalents and Investments

The following tables present the balances of assets measured at fair value on a recurring basis, by level within the fair value hierarchy, as of the dates presented (in thousands):

	December 31, 2018
	Total			Level 1		Level 2
Cash equivalents:
Money market funds	$	541,575		$	541,575	$	—
Commercial paper	3,999			—		3,999
Short-term investments:
U.S. government agency securities	646,496			—		646,496
Corporate notes and bonds	112,933			—		112,933
Commercial paper	85,506			—		85,506
Municipal securities	39,306			—		39,306
Foreign government securities	14,915			—		14,915
Certificates of deposit	4,711			—		4,711
Mortgage origination-related:
Mortgage loans held for sale	35,409			—		35,409
Interest rate lock commitments	847			—		847
Forward contracts	(125		)	—		(125		)
Total	$	1,485,572		$	541,575	$	943,997

	December 31, 2017
	Total		Level 1		Level 2
Cash equivalents:
Money market funds	$	233,508	$	233,508	$	—
Corporate notes and bonds	6,199		—		6,199
Commercial paper	3,987		—		3,987
U.S. government agency securities	1,748		—		1,748
Certificates of deposit	249		—		249
Short-term investments:
U.S. government agency securities	298,758		—		298,758
Corporate notes and bonds	44,607		—		44,607
Commercial paper	39,325		—		39,325
Municipal securities	11,459		—		11,459
Certificates of deposit	10,297		—		10,297
Foreign government securities	5,998		—		5,998
Total	$	656,135	$	233,508	$	422,627