EARNINGS PER SHARE - Schedule of Calculation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Denominator:
Weighted average number of shares of Class A common stock outstanding (in shares)									112,409,615	105,455,849	97,226,027
Basic net income (loss) per share of Class A common stock (in dollars per share)	$ (0.10)	$ 0.15	$ (0.04)	$ (0.15)	$ 0.38	$ 0.26	$ 0.31	$ 0.21	$ (0.13)	$ 1.16	$ 1.85
Denominator:
Weighted average number of shares of Class A common stock outstanding (in shares)									112,409,615	105,455,849	97,226,027
Diluted weighted average number of shares of Class A common stock outstanding (in shares)									112,409,615	106,399,783	97,652,065
Diluted net income (loss) per share of Class A common stock (in dollars per share)	$ (0.10)	$ 0.14	$ (0.04)	$ (0.15)	$ 0.37	$ 0.26	$ 0.30	$ 0.21	$ (0.13)	$ 1.15	$ 1.84
Class A Common Stock
Numerator:
Net income (loss) attributable to Class A common shareholders	$ (11,714)	$ 17,188	$ (4,189)	$ (15,728)	$ 40,650	$ 27,577	$ 32,242	$ 22,175	$ (14,445)	$ 122,645	$ 180,015
Denominator:
Weighted average number of shares of Class A common stock outstanding (in shares)									112,409,615	105,455,849	97,226,027
Basic net income (loss) per share of Class A common stock (in dollars per share)									$ (0.13)	$ 1.16	$ 1.85
Numerator:
Net income (loss) attributable to Class A common shareholders	$ (11,714)	$ 17,188	$ (4,189)	$ (15,728)	$ 40,650	$ 27,577	$ 32,242	$ 22,175	$ (14,445)	$ 122,645	$ 180,015
Amounts attributable to operating partnership’s share of Ladder Capital Corp net income (loss)									0	0	0
Additional corporate tax (expense) benefit									0	0	0
Diluted net income (loss) attributable to Class A common shareholders									$ (14,445)	$ 122,645	$ 180,015
Denominator:
Weighted average number of shares of Class A common stock outstanding (in shares)									112,409,615	105,455,849	97,226,027
Shares issuable relating to converted Class B common shareholders (in shares)									0	0	0
Diluted weighted average number of shares of Class A common stock outstanding (in shares)									112,409,615	106,399,783	97,652,065
Diluted net income (loss) per share of Class A common stock (in dollars per share)									$ (0.13)	$ 1.15	$ 1.84
Class A Common Stock | Restricted Stock
Denominator:
Incremental shares of stock based compensation (in shares)									0	943,934	426,038
Class A Common Stock | Stock Options
Denominator:
Incremental shares of stock based compensation (in shares)									0	0	0