SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Earnings Per Share (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Net income available to common shareholders	$ 261,988	$ 161,441	$ 121,027
Weighted average number of common shares outstanding (in shares)	69,256,000	58,462,000	43,142,000
Effect of dilutive stock options (in shares)	23,000	69,000	6,000
Effect of dilutive restricted stock awards (in shares)	129,000	83,000	100,000
Effect of performance share units (in shares)	18,000	0	0
Weighted average number of common shares outstanding used to calculate diluted earnings per share (in shares)	69,426,000	58,614,000	43,248,000