Available-for-Sale Securities and Fair Value Measurements (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Available-for-sale securities
Amortized Cost	$ 203,512		$ 285,483
Gross Unrealized Gains	15		35
Gross Unrealized Losses	(4)		(122)
Other Than Temporary Impairment Loss			(3,752)
Estimated Fair Value	$ 203,523		281,644
Maturity period for marketable securities
Maximum contractual maturity period	1 year
Average contractual maturity period	3 months
Proceeds from sale of available-for-sale securities	$ 57,098	$ 5,000
Theravance Biopharma
Maturity period for marketable securities
Gain on sale	1,200
Issuer of available-for-securities other than Theravance Biopharma
Maturity period for marketable securities
Proceeds from sale of available-for-sale securities	49,400
Cash and cash equivalents
Available-for-sale securities
Estimated Fair Value	76,077		95,090
Short-term marketable securities
Available-for-sale securities
Estimated Fair Value	127,446		143,698
Marketable securities
Available-for-sale securities
Estimated Fair Value	0		42,856
U.S. government securities
Available-for-sale securities
Amortized Cost	7,503		30,019
Gross Unrealized Gains	3		24
Gross Unrealized Losses	0		0
Other Than Temporary Impairment Loss			0
Estimated Fair Value	7,506		30,043
U.S. government agencies
Available-for-sale securities
Amortized Cost	69,965		34,756
Gross Unrealized Gains	9		6
Gross Unrealized Losses	(2)		(12)
Other Than Temporary Impairment Loss			0
Estimated Fair Value	69,972		34,750
Corporate notes
Available-for-sale securities
Amortized Cost	27,485		80,880
Gross Unrealized Gains	3		5
Gross Unrealized Losses	(2)		(110)
Other Than Temporary Impairment Loss			0
Estimated Fair Value	27,486		80,775
Commercial paper
Available-for-sale securities
Amortized Cost	54,702		34,469
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Other Than Temporary Impairment Loss			0
Estimated Fair Value	54,702		34,469
Ordinary shares of Theravance Biopharma
Available-for-sale securities
Amortized Cost			10,269
Gross Unrealized Gains			0
Gross Unrealized Losses			0
Other Than Temporary Impairment Loss			(3,752)
Estimated Fair Value			6,517
Money market funds
Available-for-sale securities
Amortized Cost	43,857		95,090
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Other Than Temporary Impairment Loss			0
Estimated Fair Value	$ 43,857		$ 95,090

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Represents the average maturity period for marketable securities.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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The difference between the carrying value and the sale price of equity securities, not separately or otherwise categorized as trading or available-for-sale. This element includes investments in which the entity holds a small ownership stake (generally, less than 20% of the shares outstanding) and cannot exert significant influence.

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