Available-for-Sale Securities and Fair Value Measurements (Details) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Available-for-sale securities
Amortized Cost	$ 245,905,000	$ 285,483,000
Gross Unrealized Gains	22,000	35,000
Gross Unrealized Losses	(34,000)	(122,000)
Other Than Temporary Impairment Loss		(3,752,000)
Estimated Fair Value	245,893,000us-gaap_AvailableForSaleSecurities	281,644,000us-gaap_AvailableForSaleSecurities
Maturity period for marketable securities
Maximum contractual maturity period	2 years
Average contractual maturity period	5 months
Theravance Biopharma
Maturity period for marketable securities
Gain on sale	1,200,000
Cash and cash equivalents
Available-for-sale securities
Estimated Fair Value	132,007,000	95,090,000
Short-term marketable securities
Available-for-sale securities
Estimated Fair Value	109,954,000	143,698,000
Marketable securities
Available-for-sale securities
Estimated Fair Value	3,932,000	42,856,000
U.S. government securities
Available-for-sale securities
Amortized Cost	12,505,000	30,019,000
Gross Unrealized Gains	12,000	24,000
Gross Unrealized Losses	0	0
Other Than Temporary Impairment Loss		0
Estimated Fair Value	12,517,000	30,043,000
U.S. government agencies
Available-for-sale securities
Amortized Cost	18,471,000	34,756,000
Gross Unrealized Gains	3,000	6,000
Gross Unrealized Losses	(3,000)	(12,000)
Other Than Temporary Impairment Loss		0
Estimated Fair Value	18,471,000	34,750,000
U.S. corporate notes
Available-for-sale securities
Amortized Cost	72,941,000	80,880,000
Gross Unrealized Gains	7,000	5,000
Gross Unrealized Losses	(31,000)	(110,000)
Other Than Temporary Impairment Loss		0
Estimated Fair Value	72,917,000	80,775,000
U.S. commercial paper
Available-for-sale securities
Amortized Cost	9,981,000	34,469,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Other Than Temporary Impairment Loss		0
Estimated Fair Value	9,981,000	34,469,000
Ordinary shares of Theravance Biopharma
Available-for-sale securities
Amortized Cost		10,269,000
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Other Than Temporary Impairment Loss		(3,752,000)
Estimated Fair Value		6,517,000
Money market funds
Available-for-sale securities
Amortized Cost	132,007,000	95,090,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Other Than Temporary Impairment Loss		0
Estimated Fair Value	$ 132,007,000	$ 95,090,000

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Represents the maximum 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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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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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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