Subsequent Events	3 Months Ended
Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On April 5, 2019, the Company entered into a promotion agreement (the “Promotion Agreement”) with Janssen Biotech Inc., ("Janssen") pursuant to which the Company will provide non-exclusive product detailing services to Janssen for erdafitinib (the “Product”). Pursuant to the Promotion Agreement, the Company will provide a dedicated sales team to market the Product, upon approval by the FDA, to oncologists and other targeted health care providers in the United States. Under the terms of the Promotion Agreement, Janssen maintains ownership of the New Drug Application for the Product as well as legal, regulatory, distribution, commercialization and manufacturing responsibilities for the Product, while the Company will provide product detailing services to Janssen. Following the achievement of certain sales targets in 2019 and 2020, Janssen will pay the Company (a) a service fee equal to a percentage in the low double digits of the portion of Cumulative Net Sales (as defined in the Promotion Agreement) in excess of a baseline amount during each of 2019 and 2020, and (b) potential milestone payments of up to $15 million when Cumulative Net Sales exceed certain thresholds during each of 2019 and 2020. On April 12, 2019, the Company was informed that the FDA granted accelerated approval to Janssen's Balversa (erdafitinib) for the treatment of adult patients with locally advanced or metastatic urothelial carcinoma that has a type of susceptible genetic alteration known as FGFR3 or FGFR2, and that has progressed during or following prior platinum-containing chemotherapy. On April 29, 2019, the Company, entered into a license agreement (the “License Agreement”) with Everest Medicines II Limited, a China limited company (“Everest”). Pursuant to the License Agreement, the Company granted Everest an exclusive license to develop and commercialize sacituzumab govitecan in the People’s Republic of China, Taiwan, Hong Kong, Macao, Indonesia, Philippines, Vietnam, Thailand, South Korea, Malaysia, Singapore and Mongolia. In consideration for entering into the License Agreement, Everest will make a one-time, non-refundable upfront payment to the Company in the aggregate amount of $65 million within thirty days of execution of the License Agreement. The License Agreement contains a development milestone payment of $60 million based upon the Company’s achievement of FDA approval for sacituzumab govitecan. The License Agreement also contains additional development milestone payments in a total amount of up to $180 million based upon the achievement of certain other development milestones. In addition, the License Agreement contains sales milestone payments in a total amount of up to $530 million based upon the achievement of certain sales milestones. Everest will make royalty payments to the Company based upon percentages of net sales of sacituzumab govitecan, ranging from 14% to 20%.

Subsequent Events

On April 5, 2019, the Company entered into a promotion agreement (the “Promotion Agreement”) with Janssen Biotech Inc., ("Janssen") pursuant to which the Company will provide non-exclusive product detailing services to Janssen for erdafitinib (the “Product”). Pursuant to the Promotion Agreement, the Company will provide a dedicated sales team to market the Product, upon approval by the FDA, to oncologists and other targeted health care providers in the United States. Under the terms of the Promotion Agreement, Janssen maintains ownership of the New Drug Application for the Product as well as legal, regulatory, distribution, commercialization and manufacturing responsibilities for the Product, while the Company will provide product detailing services to Janssen. Following the achievement of certain sales targets in 2019 and 2020, Janssen will pay the Company (a) a service fee equal to a percentage in the low double digits of the portion of Cumulative Net Sales (as defined in the Promotion Agreement) in excess of a baseline amount during each of 2019 and 2020, and (b) potential milestone payments of up to $15 million when Cumulative Net Sales exceed certain thresholds during each of 2019 and 2020. On April 12, 2019, the Company was informed that the FDA granted accelerated approval to Janssen's Balversa (erdafitinib) for the treatment of adult patients with locally advanced or metastatic urothelial carcinoma that has a type of susceptible genetic alteration known as FGFR3 or FGFR2, and that has progressed during or following prior platinum-containing chemotherapy.

On April 29, 2019, the Company, entered into a license agreement (the “License Agreement”) with Everest Medicines II Limited, a China limited company (“Everest”). Pursuant to the License Agreement, the Company granted Everest an exclusive license to develop and commercialize sacituzumab govitecan in the People’s Republic of China, Taiwan, Hong Kong, Macao, Indonesia, Philippines, Vietnam, Thailand, South Korea, Malaysia, Singapore and Mongolia. In consideration for entering into the License Agreement, Everest will make a one-time, non-refundable upfront payment to the Company in the aggregate amount of $65 million within thirty days of execution of the License Agreement. The License Agreement contains a development milestone payment of $60 million based upon the Company’s achievement of FDA approval for sacituzumab govitecan. The License Agreement also contains additional development milestone payments in a total amount of up to $180 million based upon the achievement of certain other development milestones. In addition, the License Agreement contains sales milestone payments in a total amount of up to $530 million based upon the achievement of certain sales milestones. Everest will make royalty payments to the Company based upon percentages of net sales of sacituzumab govitecan, ranging from 14% to 20%.