Goodwill and Other Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Carrying amounts of goodwill by operating segments

The carrying amounts of goodwill by operating segments for the nine months endedSeptember 30, 2018 were as follows:

	Community Banks		Insurance		Total
Balance at January 1, 2018	$	608,279	$	2,767	$	611,046
Addition to goodwill from acquisition	316,215		—		316,215
Adjustment to previously recorded goodwill	—		—		—
Balance at September 30, 2018	$	924,494	$	2,767	$	927,261

Summary of finite-lived intangible assets

The following table provides a summary of finite-lived intangible assets as of the dates presented:

	Gross  Carrying Amount		Accumulated Amortization			Net Carrying Amount
September 30, 2018
Core deposit intangibles	$	82,312	$	(36,497	)	$	45,815
Customer relationship intangible	1,970		(931		)	1,039
Total finite-lived intangible assets	$	84,282	$	(37,428	)	$	46,854
December 31, 2017
Core deposit intangibles	$	54,958	$	(31,586	)	$	23,372
Customer relationship intangible	1,970		(832		)	1,138
Total finite-lived intangible assets	$	56,928	$	(32,418	)	$	24,510

Current year amortization expense for finite-lived intangible assets

Current year amortization expense for finite-lived intangible assets is presented in the table below.

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Amortization expense for:
Core deposit intangibles	$	1,732	$	1,733	$	4,911	$	4,723
Customer relationship intangible	33		33		99		99
Total intangible amortization	$	1,765	$	1,766	$	5,010	$	4,822

Estimated amortization expense of finite-lived intangible assets

The estimated amortization expense of finite-lived intangible assets for the year ending December 31, 2018 and the succeeding four years is summarized as follows:

	Core Deposit Intangibles		Customer Relationship Intangible		Total
2018	$	7,041	$	131	$	7,172
2019	7,947		131		8,078
2020	6,921		131		7,052
2021	5,843		131		5,974
2022	4,923		131		5,054