GAINS FROM MORTGAGE BANKING ACTIVITIES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
GAINS FROM MORTGAGE BANKING ACTIVITIES
Contractual loan origination related fees, gross	$ 70,876	$ 64,197	$ 202,497	$ 180,655
Co-broker fees	(5,732)	(4,603)	(13,947)	(17,052)
Fair value of expected net future cash flows from servicing recognized at commitment	55,172	42,811	145,847	129,764
Fair value of expected guaranty obligation recognized at commitment	(4,387)	(3,235)	(12,852)	(10,451)
Total gains from mortgage banking activities	$ 115,929	$ 99,170	$ 321,545	$ 282,916