Subsequent Events	6 Months Ended
Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events On July 2, 2020, the Company, GB001, Inc. GB002, Inc. and GB004, Inc. (the “co-borrowers”), and GB003, Inc., GB005, Inc., GB006, Inc., GB007, Inc., GB008, Inc. and Gossamer Bio Services, Inc. (each wholly-owned subsidiaries of the Company, the “Guarantors” and together with the co-borrowers, the “Credit Parties”), entered into the second amendment to the Credit Facility, to, among other things (i) designate the Company, GB002, Inc. and GB004, Inc. as co-borrowers, in which each such entity assumes the obligations under the Credit Facility as a co-borrower, joins in, adopts and becomes a co-borrower under the Credit Facility and ceases to be a Guarantor under the Credit Facility; (ii) extend the maturity date to January 1, 2025; (iii) increase the annual interest rate equal to the sum of (a) one-month LIBOR (customarily defined, with a change to prime rate if LIBOR funding becomes unlawful or impractical) plus (b) 7.00%, subject to a LIBOR floor of 2.00%; (iv) extend the period of time the co-borrowers are required to make interest-only payments to July 1, 2022; and (v) amend the ability to access the remaining $120.0 million in term loan commitments in two additional tranches (each $60.0 million), subject to amended specified availability periods, clinical development milestones and minimum cash requirements. The second and third tranches are available no earlier than the satisfaction of the applicable funding conditions, including the applicable clinical development milestones, and no later than December 31, 2022.

Subsequent Events

6 Months Ended

Jun. 30, 2020

10. Subsequent Events

On July 2, 2020, the Company, GB001, Inc. GB002, Inc. and GB004, Inc. (the “co-borrowers”), and GB003, Inc., GB005, Inc., GB006, Inc., GB007, Inc., GB008, Inc. and Gossamer Bio Services, Inc. (each wholly-owned subsidiaries of the Company, the “Guarantors” and together with the co-borrowers, the “Credit Parties”), entered into the second amendment to the Credit Facility, to, among other things (i) designate the Company, GB002, Inc. and GB004, Inc. as co-borrowers, in which each such entity assumes the obligations under the Credit Facility as a co-borrower, joins in, adopts and becomes a co-borrower under the Credit Facility and ceases to be a Guarantor under the Credit Facility; (ii) extend the maturity date to January 1, 2025; (iii) increase the annual interest rate equal to the sum of (a) one-month LIBOR (customarily defined, with a change to prime rate if LIBOR funding becomes unlawful or impractical) plus (b) 7.00%, subject to a LIBOR floor of 2.00%; (iv) extend the period of time the co-borrowers are required to make interest-only payments to July 1, 2022; and (v) amend the ability to access the remaining $120.0 million in term loan commitments in two additional tranches (each $60.0 million), subject to amended specified availability periods, clinical development milestones and minimum cash requirements. The second and third tranches are available no earlier than the satisfaction of the applicable funding conditions, including the applicable clinical development milestones, and no later than December 31, 2022.