Net Income Per Share - Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income attributable to Innoviva stockholders, basic	$ 29,581	$ 16,845
Add: interest expense on 2023 Notes	1,412	1,407
Net income attributable to Innoviva stockholders, diluted	$ 30,993	$ 18,252
Denominator:
Weighted-average shares used to compute basic net income per share attributable to Innoviva stockholders	100,604	107,487
Dilutive effect of 2023 Notes	12,189	12,189
Dilutive effect of options and awards granted under equity incentive plan and employee stock purchase plan	773	660
Weighted-average shares used to compute diluted net income per share attributable to Innoviva stockholders	113,566	120,336
Net income per share attributable to Innoviva stockholders
Basic net income per share	$ 0.29	$ 0.16
Diluted net income per share	$ 0.27	$ 0.15
Convertible senior notes \| 2025 Notes
Net income (loss) per share
Dilutive effect of 2025 Notes	0
Convertible senior notes \| 2025 Notes \| Common Stock
Net income (loss) per share
Conversion price of convertible notes into common stock (in dollars per share)	$ 17.26

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the treasury stock method.

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The price per share of the conversion feature embedded in the debt instrument.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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