Available-for-Sale Securities and Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	$ 245,893	$ 281,644
U.S. government securities
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	12,517	30,043
U.S. government agencies
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	18,471	34,750
U.S. corporate notes
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	72,917	80,775
U.S. commercial paper
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	9,981	34,469
Ordinary shares of Theravance Biopharma
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value		6,517
Money market funds
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	132,007	95,090
Recurring basis | Total
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	245,893	281,644
Recurring basis | Total | U.S. government securities
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	12,517	30,043
Recurring basis | Total | U.S. government agencies
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	18,471	34,750
Recurring basis | Total | U.S. corporate notes
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	72,917	80,775
Recurring basis | Total | U.S. commercial paper
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	9,981	34,469
Recurring basis | Total | Ordinary shares of Theravance Biopharma
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value		6,517
Recurring basis | Total | Money market funds
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	132,007	95,090
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	144,524	131,650
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | U.S. government securities
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	12,517	30,043
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | U.S. government agencies
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | U.S. corporate notes
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | U.S. commercial paper
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | Ordinary shares of Theravance Biopharma
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value		6,517
Recurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | Money market funds
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	132,007	95,090
Recurring basis | Significant Other Observable Inputs, Level 2
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	101,369	149,994
Recurring basis | Significant Other Observable Inputs, Level 2 | U.S. government securities
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Other Observable Inputs, Level 2 | U.S. government agencies
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	18,471	34,750
Recurring basis | Significant Other Observable Inputs, Level 2 | U.S. corporate notes
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	72,917	80,775
Recurring basis | Significant Other Observable Inputs, Level 2 | U.S. commercial paper
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	9,981	34,469
Recurring basis | Significant Other Observable Inputs, Level 2 | Ordinary shares of Theravance Biopharma
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value		0
Recurring basis | Significant Other Observable Inputs, Level 2 | Money market funds
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Unobservable Inputs, Level 3
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Unobservable Inputs, Level 3 | U.S. government securities
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Unobservable Inputs, Level 3 | U.S. government agencies
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Unobservable Inputs, Level 3 | U.S. corporate notes
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Unobservable Inputs, Level 3 | U.S. commercial paper
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Recurring basis | Significant Unobservable Inputs, Level 3 | Ordinary shares of Theravance Biopharma
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value		0
Recurring basis | Significant Unobservable Inputs, Level 3 | Money market funds
Estimated fair values of entity's financial assets and liabilities
Total assets measured at fair value	0	0
Nonrecurring basis | Total
Estimated fair values of entity's financial assets and liabilities
Total fair value of liabilities	693,020	653,506
Nonrecurring basis | Total | Convertible subordinated notes due 2023
Estimated fair values of entity's financial assets and liabilities
Convertible subordinated notes due 2023	223,220	197,905
Nonrecurring basis | Total | Non-recourse notes payable due 2029
Estimated fair values of entity's financial assets and liabilities
Non-recourse notes due 2029	469,800	456,411
Nonrecurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1
Estimated fair values of entity's financial assets and liabilities
Total fair value of liabilities	0	0
Nonrecurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | Convertible subordinated notes due 2023
Estimated fair values of entity's financial assets and liabilities
Convertible subordinated notes due 2023	0	0
Nonrecurring basis | Quoted Prices in Active Markets for Identical Assets, Level 1 | Non-recourse notes payable due 2029
Estimated fair values of entity's financial assets and liabilities
Non-recourse notes due 2029	0	0
Nonrecurring basis | Significant Other Observable Inputs, Level 2
Estimated fair values of entity's financial assets and liabilities
Total fair value of liabilities	693,020	653,506
Nonrecurring basis | Significant Other Observable Inputs, Level 2 | Convertible subordinated notes due 2023
Estimated fair values of entity's financial assets and liabilities
Convertible subordinated notes due 2023	223,220	197,095
Nonrecurring basis | Significant Other Observable Inputs, Level 2 | Non-recourse notes payable due 2029
Estimated fair values of entity's financial assets and liabilities
Non-recourse notes due 2029	469,800	456,411
Nonrecurring basis | Significant Unobservable Inputs, Level 3
Estimated fair values of entity's financial assets and liabilities
Total fair value of liabilities	0	0
Nonrecurring basis | Significant Unobservable Inputs, Level 3 | Convertible subordinated notes due 2023
Estimated fair values of entity's financial assets and liabilities
Convertible subordinated notes due 2023	0	0
Nonrecurring basis | Significant Unobservable Inputs, Level 3 | Non-recourse notes payable due 2029
Estimated fair values of entity's financial assets and liabilities
Non-recourse notes due 2029	$ 0	$ 0