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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Summary of Significant Accounting Policies - Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016	Sep. 30, 2017 USD ($) item	Sep. 30, 2016
Segment Information
Number of operating segments \| item			1
Bayer \| Revenues percentage \| Customer concentration
Segment Information
Percentages of revenue recognized				29.00%
CytomX \| Revenues percentage \| Customer concentration
Segment Information
Percentages of revenue recognized	1.00%	8.00%	20.00%	6.00%
Roche \| Revenues percentage \| Customer concentration
Segment Information
Percentages of revenue recognized	77.00%	81.00%	27.00%	56.00%
Sanofi \| Revenues percentage \| Customer concentration
Segment Information
Percentages of revenue recognized			47.00%
Takeda \| Revenues percentage \| Customer concentration
Segment Information
Percentages of revenue recognized	13.00%	9.00%	4.00%	3.00%
Maximum \| Accounting Standards Update 2014-09
Recent Accounting Pronouncements
Number of contracts requiring evaluation \| item			20
Federal \| New accounting pronouncement \| Accounting Standards Update 2016-09
Recent Accounting Pronouncements
Net deferred tax assets	$ 9.2		$ 9.2
Valuation allowance	9.2		9.2
State \| New accounting pronouncement \| Accounting Standards Update 2016-09
Recent Accounting Pronouncements
Net deferred tax assets	1.2		1.2
Valuation allowance	$ 1.2		$ 1.2