GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)

9 Months Ended

Sep. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in Carrying Amount of Goodwill

	Three months ended				Nine months ended
	September 30,				September 30,
(Dollars in thousands)	2020		2019		2020		2019
Balance at beginning of period	$	937,771	$	879,727	$	937,771	$	880,251
Goodwill resulting from business combinations	0		57,962		0		57,438
Balance at end of period	$	937,771	$	937,689	$	937,771	$	937,689

Finite-Lived Intangible Assets [Line Items]

Schedule of Finite-Lived Intangible Assets [Table Text Block]

(Dollars in thousands)	September 30, 2020				December 31, 2019
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Amortized intangible assets
Core deposit intangibles	$	51,031	$	(25,930)	$	51,031	$	(21,149)
Customer list	39,420		(3,883)		39,420		(1,195)
Other	10,093		(3,312)		10,093		(1,999)
Total	$	100,544	$	(33,125)	$	100,544	$	(24,343)