Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenue	$ 156,846	$ 235,201	$ 234,495
Total gross profit	81,135	89,651	115,989
Operating expenses:
Research and development	81,591	138,094	92,216
Sales and marketing	60,130	85,248	84,077
General and administrative	70,688	139,120	128,802
Amortization of acquired intangible assets	0	8,411	8,136
Impairment of intangible assets and goodwill	0	449,680	0
Restructuring	24,948	15,275	0
Total operating expenses	237,357	835,828	313,231
Loss from operations	(156,222)	(746,177)	(197,242)
Interest expense	(30,811)	(24,790)	(11,279)
Other income (expense), net	7,248	4,916	493
Loss before income taxes	(179,785)	(766,051)	(208,028)
Software platform
Segment Reporting Information [Line Items]
Total revenue	101,204	113,589	127,239
Professional Services
Segment Reporting Information [Line Items]
Total revenue	8,345	7,835	6,944
Blend Platform segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	109,549	121,424	134,183
Total gross profit	76,459	75,214	91,108
Blend Platform segment | Operating Segments | Software platform
Segment Reporting Information [Line Items]
Total revenue	101,204	113,589	127,239
Total gross profit	79,179	82,883	96,976
Blend Platform segment | Operating Segments | Professional Services
Segment Reporting Information [Line Items]
Total revenue	8,345	7,835	6,944
Total gross profit	(2,720)	(7,669)	(5,868)
Title segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	47,297	113,777	100,312
Total gross profit	$ 4,676	$ 14,437	$ 24,881