Available-for-Sale Securities and Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale securities
Amortized Cost	$ 285,483	$ 502,669
Gross Unrealized Gains	35	172
Gross Unrealized Losses	(122)	(10)
Other Than Temporary Impairment Loss	(3,752)	0	0
Estimated Fair Value	281,644us-gaap_AvailableForSaleSecurities	502,831us-gaap_AvailableForSaleSecurities
Maturity period for marketable securities
Maximum contractual maturity period	2 years
Average contractual maturity period	8 months
Amount of marketable securities sold	7,211	22,600	49,729
Cash and cash equivalents
Available-for-sale securities
Estimated Fair Value	95,090	125,009
Short-term marketable securities
Available-for-sale securities
Estimated Fair Value	143,698	321,615
Marketable securities
Available-for-sale securities
Estimated Fair Value	42,856	55,374
Restricted cash
Available-for-sale securities
Estimated Fair Value	0	833
U.S. government securities
Available-for-sale securities
Amortized Cost	30,019	42,104
Gross Unrealized Gains	24	55
Gross Unrealized Losses	0	(1)
Other Than Temporary Impairment Loss	0	0
Estimated Fair Value	30,043	42,158
U.S. government agencies
Available-for-sale securities
Amortized Cost	34,756	141,278
Gross Unrealized Gains	6	61
Gross Unrealized Losses	(12)	(8)
Other Than Temporary Impairment Loss	0	0
Estimated Fair Value	34,750	141,331
U.S. corporate notes
Available-for-sale securities
Amortized Cost	80,880	94,923
Gross Unrealized Gains	5	54
Gross Unrealized Losses	(110)	0
Other Than Temporary Impairment Loss	0	0
Estimated Fair Value	80,775	94,977
U.S. commercial paper
Available-for-sale securities
Amortized Cost	34,469	102,021
Gross Unrealized Gains	0	2
Gross Unrealized Losses	0	(1)
Other Than Temporary Impairment Loss	0	0
Estimated Fair Value	34,469	102,022
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	95,090	122,343
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Other Than Temporary Impairment Loss	0	0
Estimated Fair Value	$ 95,090	$ 122,343

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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 amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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