Goodwill and Acquired Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The following table presents changes in the carrying amount of goodwill:

	For the Year Ended December 31,
	2017		2016		2015
	(In thousands)
Beginning of year	$	64,649	$	25,211	$	25,309
Changes from business combinations		82,929		39,438		0
Other		0		0		(98)
Total Goodwill	$	147,578	$	64,649	$	25,211

Acquired intangible assets consist of core deposit intangibles

Acquired intangible assets consist of core deposit intangibles ("CDI"), which are intangible assets arising from the purchase of deposits separately or from bank acquisitions. The change in balance for CDI is as follows:

	For the Year Ended December 31,
	2017		2016		2015
	(In thousands)
Beginning of year	$	14,572	$	8,594	$	7,454
Acquired CDI		7,726		8,464		2,564
Amortization expense		(3,361)		(2,486)		(1,424)
End of year	$	18,937	$	14,572	$	8,594
				(In months)
Remaining Average Amortization Period for CDI		63		64		67

Gross Carrying Amount and Accumulated Amortization of Intangible Asset

The gross carrying amount and accumulated amortization of the Company's CDI subject to amortization as of:

	December 31, 2017				December 31, 2016
	Gross				Gross
	Carrying		Accumulated		Carrying		Accumulated
	Amount		Amortization		Amount		Amortization
	(In thousands)
Deposit base	$	26,522	$	(7,585)	$	18,796	$	(4,224)