Deposit Accounts (Tables)

12 Months Ended

Dec. 31, 2017

Deposits [Abstract]

Schedule of components of deposit accounts and weighted average interest rates

Deposit accounts and weighted average interest rates consisted of the following at December 31:

	2017		Weighted Average Interest Rate		2016		Weighted Average Interest Rate
	(dollars in thousands)
Transaction accounts
Noninterest-bearing checking	$	2,226,848	—	%	$	1,185,768	—	%
Interest-bearing checking	365,193		0.13	%	182,893		0.11	%
Money market	2,181,571		0.48	%	1,100,787		0.34	%
Savings	227,436		0.13	%	101,574		0.14	%
Total transaction accounts	5,001,048		0.21	%	2,571,022		0.16	%
Certificates of deposit accounts
Less than 100,000	192,409		0.85	%	121,148		0.74	%
$100,000 through $250,000	369,748		1.01	%	153,103		0.82	%
Greater than $250,000	522,663		1.26	%	300,308		0.74	%
Total certificates of deposit accounts	1,084,820		1.10	%	574,559		0.76	%
Total deposits	$	6,085,868	0.33	%	$	3,145,581	0.27	%

Schedule of aggregate annual maturities of certificates of deposit accounts

The aggregate annual maturities of certificates of deposit accounts at December 31, 2017 are as follows:

	2017
	Balance		Weighted Average Interest Rate
	(dollars in thousands)
Within 3 months	$	318,794	0.93	%
4 to 6 months	250,026		1.07	%
7 to 12 months	279,192		1.18	%
13 to 24 months	175,005		1.24	%
25 to 36 months	29,270		1.33	%
37 to 60 months	22,936		1.44	%
Over 60 months	9,597		1.13	%
Total	$	1,084,820	1.10	%

Schedule of interest expense on deposit accounts

Interest expense on deposit accounts for the years ended December 31 is summarized as follows:

	2017		2016		2015
	(dollars in thousands)
Checking accounts	$	365	$	200	$	165
Money market accounts	6,720		3,641		2,426
Savings	251		151		141
Certificates of deposit accounts	6,035		4,399		3,898
Total	$	13,371	$	8,391	$	6,630