NET INCOME (LOSS) PER SHARE - Anti-dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Anti-dilutive securities
Anti-dilutive securities (in shares)	4,073	19,838	20,340
Former Employees Transferred To Theravance Biopharma Spin Off
Anti-dilutive securities
Anti-dilutive securities (in shares)	2,800
Equity incentive plans and ESPP
Anti-dilutive securities
Anti-dilutive securities (in shares)	4,073	6,934	8,011
Unvested RSAs | Former Employees Transferred To Theravance Biopharma Spin Off
Anti-dilutive securities
Anti-dilutive securities (in shares)	200	1,000
Conversion of 2023 Notes
Anti-dilutive securities
Anti-dilutive securities (in shares)	0	12,904	12,329
Stock options | Former Employees Transferred To Theravance Biopharma Spin Off
Anti-dilutive securities
Anti-dilutive securities (in shares)	2,900	4,100
RSUs | Former Employees Transferred To Theravance Biopharma Spin Off
Anti-dilutive securities
Anti-dilutive securities (in shares)	100	400