GOODWILL AND CORE DEPOSIT INTANGIBLES

Goodwill

	Year Ended December 31,
	2018		2017
Net carrying value at beginning of period	$	444.7	$	212.8
Acquisitions and measurement period adjustments	102.0		231.9
Net carrying value at end of period	$	546.7	$	444.7

The Company performed its annual goodwill impairment qualitative assessment as of July 1, 2018, 2017, and 2016 and determined the Company’s goodwill was not considered impaired. In addition, there were no events or circumstances that occurred during the second half of 2018 that would more-likely-than-not reduce the fair value of a reporting unit below its carrying value, the Company did not perform interim testing as of December 31, 2018.

Core deposit intangibles (“CDI”) The following table sets forth activity for identifiable core deposit intangibles subject to amortization:

	Year Ended December 31,
	2018			2017
Gross CDI, beginning of period	$	74.0		$	29.2
Established through acquisitions	15.7			48.0
Reductions due to sale of accounts	—			(3.2		)
Accumulated amortization	(32.8		)	(24.9		)
Net CDI, end of period	$	56.9		$	49.1

Amortization expense of CDI assets was $7.9 million, $5.5 million and $3.4 million for the fiscal years ended December 31, 2018, 2017 and 2016, respectively.

CDI are evaluated for impairment if events and circumstances indicate a possible impairment. The CDI are amortized using an accelerated method based on the estimated weighted average useful lives of the related deposits, which is generally ten years.

In 2017, the Company sold the custodial rights to our Health Savings Account (“HSA”) portfolio to HealthEquity, Inc. for $6.2 million, of which $3.2 million was attributable to BOTC acquired deposits which were sold at fair market value.

The following table provides estimated future CDI amortization expense:



Years ending December 31,
2019	$	8.9
2020	8.1
2021	7.5
2022	6.9
2023	6.3
Thereafter	19.2
Total	$	56.9