Checkpoint Therapeutics, Inc. Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions			12 Months Ended
	Jan. 01, 2020	Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018	Mar. 17, 2015
Equity Method Investment, Annual Equity Fee, Percentage					2.50%
Fortress Biotech, Inc [Member]
Equity Method Investment, Annual Equity Fee, Percentage	2.50%	2.50%	2.50%
Stock Issued During Period, Shares, New Issues	1,459,305	960,428	441,816	178,292
Research and development [Member]
Stock Issued During Period, Value, Issued for Services			$ 2.5	$ 1.7