Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Marketable Securities and Free Share Asset/Liability

The fair value measurements of the Company’s cash equivalents, available-for-sale marketable securities and the free share asset/liability are identified at the following levels within the fair value hierarchy (in thousands):

	March 31, 2019
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	15,233	$	15,233	$	—	$	—
Commercial paper securities		4,990		—		4,990		—
Total		20,223		15,233		4,990		—
Marketable securities:
Commercial paper securities		180,399		—		180,399		—
Corporate debt securities		70,948		—		70,948		—
U.S. government-sponsored entity debt securities		18,681		—		18,681		—
Total		270,028		—		270,028		—
Total cash equivalents and marketable securities	$	290,251	$	15,233	$	275,018	$	—
Free shares asset	$	355	$	—	$	—	$	355

	December 31, 2018
	Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	103,291	$	103,291	$	—	$	—
Total		103,291		103,291		—		—
Marketable securities:
Commercial paper securities		177,224		—		177,224		—
Corporate debt securities		63,870		—		63,870		—
U.S. government-sponsored entity debt securities		18,621		—		18,621		—
Total		259,715		—		259,715		—
Total cash equivalents and marketable securities	$	363,006	$	103,291	$	259,715	$	—
Liabilities
Free shares liability	$	154	$	—	$	—	$	154
Total	$	154	$	—	$	—	$	154

Summary of Estimated Fair Value of Free Shares Valuation Assumptions

The assumptions used in this simulation model are reviewed on a quarterly basis and adjusted, as needed. Subsequent changes in the fair value of the free shares are recorded in operating expenses in the condensed consolidated statement of operations.

Free Shares valuation assumptions:	March 31, 2019			December 31, 2018
Sangamo Stock Price (USD)	$	9.54		$	11.48
TxCell Stock Price (EUR)	$	2.36		$	2.58
EUR/ USD Exchange Rate		0.89			0.87
Estimated Correlation Sangamo and TxCell Stock Prices		50.0	%		—
Sangamo Stock Price (USD) Volatility Estimate		87.7	%		79.9	%
TxCell Stock Price (EUR) Volatility Estimate		82.8	%		8.6	%
EUR/ USD Exchange Rate Volatility Estimate		7.2	%		7.7	%
Risk Free Rate	Varies by expected exercise date			Varies by expected exercise date