Share-based Compensation (Narrative) (Details) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 01, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Feb. 10, 2021	Apr. 01, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price		$ 3.87		$ 3.87		$ 4.15	$ 5.35	$ 12.00
Share-based compensation, options outstanding, weighted average remaining contractual term (years)				7 years 9 months 7 days		7 years 1 month 9 days
Share based compensation, options outstanding, aggregate intrinsic value		$ 5,037,000		$ 5,037,000		$ 7,365,000
Options outstanding		24,963,833		24,963,833		16,000,685
Options outstanding, Exercise price		$ 4.80		$ 4.80		$ 5.29
Common stock issued for option exercises, shares				361,399
Stock options exercised, intrinsic value				$ 434,000
Options Outstanding, Value, Exercised		$ 230,000	$ 365,000	$ 1,358,000	$ 649,000
Share based compensation, options granted				9,821,493	4,857,676
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vested				962,502		962,502
Common stock issued for option exercises, shares				0		0
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for recognition of compensation expense				3 years
Share-based compensation, options outstanding, weighted average remaining contractual term (years)				5 years 1 month 6 days
Share based compensation, options outstanding, aggregate intrinsic value		$ 200,000		$ 200,000		$ 500,000
Options outstanding		835,000		835,000		835,000
Options outstanding, Exercise price		$ 3.64		$ 3.64		$ 3.64
Options vested				835,000		835,000
Common stock issued for option exercises, shares				0		0
2016 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance						21,785,738
Additional units available for grant	6,861,201
Increase in authorized shares as a percentage of common stock issued	4.00%
Unrecognized compensation expense		$ 31,300,000		$ 31,300,000		$ 11,900,000
Weighted average period for recognition of compensation expense				2 years 2 months 12 days		1 year 10 months 24 days
Stock compensation expense		3,948,000	$ 2,620,000	$ 7,621,000	$ 4,658,000
2016 Equity Incentive Plan [Member] \| Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, options outstanding, weighted average remaining contractual term (years)				5 years 2 months 12 days
Share based compensation, options outstanding, aggregate intrinsic value		$ 0		$ 0		$ 300,000
Options outstanding		1,290,000		1,290,000
Options outstanding, Exercise price		$ 4.06		$ 4.06
Service period				3 years
2014 Long-Term Incentive Plan (“LTIP”) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued for option exercises, shares				0
Equity instruments granted				9,750		9,750
Equity instruments base price				$ 6.00
Equity instrument payable, common stock value percent above grant price				333.00%
Equity instrument payable, common stock value				$ 20.00
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance						2,551,180
Stock compensation expense				$ 0
Share based compensation, options granted				94,420	98,840
Maximum [Member] \| 2016 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares annual percentage				4.00%

Kadmon Holdings, Inc. 10-Q