Summary of Significant Accounting Policies and Basis of Presentation (Tables)

12 Months Ended

Dec. 31, 2019

Depreciation is recorded using the straight-line method over the estimated useful lives of the respective assets, which are as follows:

Asset		Estimated useful life
Computer equipment		3 years
Furniture, fixtures and other		5 years
Laboratory equipment		5 years
Leasehold improvements		Shorter of useful life or remaining lease term

Impact of Adopting ASC 842 on the Financial Statements

	January 1, 2019 Prior to ASC 842 Adoption		ASC 842 Adjustment			January 1, 2019 As Adjusted
Consolidated Balance Sheet Data (in thousands):
Prepaid expenses and other current assets⁽¹⁾	$	9,658	$	(553	)	$	9,105
Operating lease assets⁽²⁾	$	—	$	26,087		$	26,087
Deferred rent⁽³⁾⁽⁴⁾	$	1,026	$	(1,026	)	$	—
Deferred rent non-current⁽³⁾	$	11,052	$	(11,052	)	$	—
Operating lease liabilities⁽⁵⁾	$	—	$	4,930		$	4,930
Non-current operating lease liabilities⁽⁵⁾	$	—	$	32,682		$	32,682

(1) Represents reclassification of prepaid rent to operating lease assets.
(2) Represents capitalization of operating lease assets and reclassification of equipment licenses from prepaid expenses to operating lease assets, offset by reclassification of deferred rent to operating lease assets.
(3) Represents reclassification of deferred rent and tenant incentives to operating lease assets.
(4) As of December 31, 2018, the deferred rent balance was $1,202, which included $176 of sublease income received prior to year-end but not due until January 1, 2019.
(5) Represents recognition of operating lease liabilities.