PARENT COMPANY ONLY FINANCIAL STATEMENTS - CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Statement of Income Captions [Line Items]
NET INCOME (LOSS)	$ 34,136	$ (972)	$ 15,439
OTHER COMPREHENSIVE INCOME BEFORE TAX:
Change in unrealized (loss) gain on securities available-for-sale	(8,853)	(1,757)	(992)
Total other comprehensive income (loss) before tax	(8,853)	(1,757)	(992)
DEFERRED TAX (BENEFIT) EXPENSE RELATED TO OTHER COMPREHENSIVE (LOSS) INCOME	(3,099)	(615)	(347)
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(5,754)	(1,142)	(645)
COMPREHENSIVE INCOME (LOSS)	28,382	(2,114)	14,794
Green Bancorp, Inc.
Condensed Statement of Income Captions [Line Items]
NET INCOME (LOSS)	34,136	(972)	15,439
OTHER COMPREHENSIVE INCOME BEFORE TAX:
Change in unrealized (loss) gain on securities available-for-sale	(8,853)	(1,757)	(992)
Total other comprehensive income (loss) before tax	(8,853)	(1,757)	(992)
DEFERRED TAX (BENEFIT) EXPENSE RELATED TO OTHER COMPREHENSIVE (LOSS) INCOME	(3,099)	(615)	(347)
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(5,754)	(1,142)	(645)
COMPREHENSIVE INCOME (LOSS)	$ 28,382	$ (2,114)	$ 14,794