Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill and Intangible Assets

The following table sets forth activity for goodwill and other intangible assets for the period:

	Years Ended December 31,
	2017			2016			2015
	(in thousands)
Goodwill, beginning of period	$	382,762		$	382,762		$	382,537
Established through acquisitions and provisional period adjustments (1)	383,080			—			225
Total goodwill, end of period	765,842			382,762			382,762
Other intangible assets, net
Core deposit intangible:
Gross core deposit intangible balance, beginning of period	58,598			58,598			58,598
Accumulated amortization, beginning of period	(41,886		)	(35,940		)	(29,058		)
Core deposit intangible, net, beginning of period	16,712			22,658			29,540
Established through acquisition	46,875			—			—
CDI current period amortization	(6,333		)	(5,946		)	(6,882		)
Total core deposit intangible, end of period	57,254			16,712			22,658
Intangible assets not subject to amortization	919			919			919
Other intangible assets, net at end of period	58,173			17,631			23,577
Total goodwill and intangible assets, end of period	$	824,015		$	400,393		$	406,339

Estimated Future Amortization Expense of Core Deposit Intangibles

The following table provides the estimated future amortization expense of core deposit intangibles for the succeeding five years:

Years Ending December 31,	(in thousands)
2018	$	12,235
2019	10,479
2020	8,724
2021	7,264
2022	5,880