Loans and Allowance for Loan Losses - Activity in the Allowance for Loan Losses, by Portfolio Segment, for the Current Year (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	$ 60,555,000	$ 47,614,000	$ 56,694,000	$ 42,086,000
Provision for loan losses	7,079,000	9,033,000	16,364,000	18,183,000
Balance, end of year	64,179,000	53,776,000	64,179,000	53,776,000
Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	59,243,000	47,207,000	56,599,000	41,668,000
Provision for loan losses	7,079,000	7,264,000	13,900,000	16,346,000
Charge-offs	(4,082,000)	(3,329,000)	(9,099,000)	(7,600,000)
Recoveries	827,000	590,000	1,667,000	1,318,000
Net charge-offs	(3,255,000)	(2,739,000)	(7,432,000)	(6,282,000)
Balance, end of year	63,067,000	51,732,000	63,067,000	51,732,000
Period-end amount allocated to:
Loans individually evaluated for impairment	6,239,000	445,000	6,239,000	445,000	$ 684,000
Loans collectively evaluated for impairment	56,828,000	51,287,000	56,828,000	51,287,000	55,915,000
Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	2,392,000	3,393,000	2,419,000	3,596,000
Provision for loan losses	642,000	1,079,000	1,848,000	1,838,000
Charge-offs	(905,000)	(1,366,000)	(2,438,000)	(2,422,000)
Recoveries	331,000	133,000	631,000	227,000
Net charge-offs	(574,000)	(1,233,000)	(1,807,000)	(2,195,000)
Balance, end of year	2,460,000	3,239,000	2,460,000	3,239,000
Period-end amount allocated to:
Loans individually evaluated for impairment	0	0	0	0	0
Loans collectively evaluated for impairment	2,460,000	3,239,000	2,460,000	3,239,000	2,419,000
Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	20,578,000	9,601,000	20,514,000	7,007,000
Provision for loan losses	2,956,000	6,897,000	4,830,000	11,183,000
Charge-offs	(1,867,000)	(790,000)	(3,835,000)	(2,551,000)
Recoveries	72,000	59,000	230,000	128,000
Net charge-offs	(1,795,000)	(731,000)	(3,605,000)	(2,423,000)
Balance, end of year	21,739,000	15,767,000	21,739,000	15,767,000
Period-end amount allocated to:
Loans individually evaluated for impairment	5,744,000	18,000	5,744,000	18,000	437,000
Loans collectively evaluated for impairment	15,995,000	15,749,000	15,995,000	15,749,000	20,077,000
Loans, Excluding Acquired Loans | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	32,354,000	30,414,000	29,743,000	27,281,000
Provision for loan losses	2,681,000	(1,461,000)	5,524,000	1,825,000
Charge-offs	(271,000)	(161,000)	(645,000)	(616,000)
Recoveries	153,000	112,000	295,000	414,000
Net charge-offs	(118,000)	(49,000)	(350,000)	(202,000)
Balance, end of year	34,917,000	28,904,000	34,917,000	28,904,000
Period-end amount allocated to:
Loans individually evaluated for impairment	495,000	427,000	495,000	427,000	247,000
Loans collectively evaluated for impairment	34,422,000	28,477,000	34,422,000	28,477,000	29,496,000
Loans, Excluding Acquired Loans | Credit Card | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	3,919,000	3,799,000	3,923,000	3,784,000
Provision for loan losses	800,000	749,000	1,698,000	1,500,000
Charge-offs	(1,039,000)	(1,012,000)	(2,181,000)	(2,011,000)
Recoveries	271,000	286,000	511,000	549,000
Net charge-offs	(768,000)	(726,000)	(1,670,000)	(1,462,000)
Balance, end of year	3,951,000	3,822,000	3,951,000	3,822,000
Period-end amount allocated to:
Loans individually evaluated for impairment	0	0	0	0	0
Loans collectively evaluated for impairment	3,951,000	3,822,000	3,951,000	3,822,000	$ 3,923,000
Loans Acquired
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	1,312,000	407,000	95,000	418,000
Provision for loan losses	0	1,769,000	2,464,000	1,837,000
Charge-offs	(1,100,000)	(132,000)	(2,347,000)	(211,000)
Recoveries	900,000		900,000
Balance, end of year	$ 1,112,000	$ 2,044,000	$ 1,112,000	$ 2,044,000