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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	$ 64,179,000	$ 53,776,000	$ 56,694,000	$ 42,086,000
Provision for loan losses	21,973,000	10,345,000	38,337,000	28,528,000
Balance, end of year	66,590,000	56,703,000	66,590,000	56,703,000
Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	63,067,000	51,732,000	56,599,000	41,668,000
Provision for loan losses	21,973,000	10,345,000	35,873,000	26,691,000
Charge-offs	(20,812,000)	(7,784,000)	(29,911,000)	(15,384,000)
Recoveries	1,765,000	1,065,000	3,432,000	2,383,000
Net charge-offs	(19,047,000)	(6,719,000)	(26,479,000)	(13,001,000)
Balance, end of year	65,993,000	55,358,000	65,993,000	55,358,000
Period-end amount allocated to:
Loans individually evaluated for impairment	5,279,000	459,000	5,279,000	459,000	$ 684,000
Loans collectively evaluated for impairment	60,714,000	54,899,000	60,714,000	54,899,000	55,915,000
Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	2,460,000	3,239,000	2,419,000	3,596,000
Provision for loan losses	(528,000)	729,000	1,320,000	2,567,000
Charge-offs	(1,059,000)	(1,321,000)	(3,497,000)	(3,743,000)
Recoveries	1,422,000	176,000	2,053,000	403,000
Net charge-offs	363,000	(1,145,000)	(1,444,000)	(3,340,000)
Balance, end of year	2,295,000	2,823,000	2,295,000	2,823,000
Period-end amount allocated to:
Loans individually evaluated for impairment	0	0	0	0	0
Loans collectively evaluated for impairment	2,295,000	2,823,000	2,295,000	2,823,000	2,419,000
Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	21,739,000	15,767,000	20,514,000	7,007,000
Provision for loan losses	19,150,000	3,589,000	23,980,000	14,772,000
Charge-offs	(17,729,000)	(592,000)	(21,564,000)	(3,143,000)
Recoveries	65,000	450,000	295,000	578,000
Net charge-offs	(17,664,000)	(142,000)	(21,269,000)	(2,565,000)
Balance, end of year	23,225,000	19,214,000	23,225,000	19,214,000
Period-end amount allocated to:
Loans individually evaluated for impairment	4,620,000	191,000	4,620,000	191,000	437,000
Loans collectively evaluated for impairment	18,605,000	19,023,000	18,605,000	19,023,000	20,077,000
Loans, Excluding Acquired Loans | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	34,917,000	28,904,000	29,743,000	27,281,000
Provision for loan losses	2,405,000	5,308,000	7,929,000	7,133,000
Charge-offs	(907,000)	(4,952,000)	(1,552,000)	(5,568,000)
Recoveries	55,000	210,000	350,000	624,000
Net charge-offs	(852,000)	(4,742,000)	(1,202,000)	(4,944,000)
Balance, end of year	36,470,000	29,470,000	36,470,000	29,470,000
Period-end amount allocated to:
Loans individually evaluated for impairment	659,000	268,000	659,000	268,000	247,000
Loans collectively evaluated for impairment	35,811,000	29,202,000	35,811,000	29,202,000	29,496,000
Loans, Excluding Acquired Loans | Credit Card | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	3,951,000	3,822,000	3,923,000	3,784,000
Provision for loan losses	946,000	719,000	2,644,000	2,219,000
Charge-offs	(1,117,000)	(919,000)	(3,298,000)	(2,930,000)
Recoveries	223,000	229,000	734,000	778,000
Net charge-offs	(894,000)	(690,000)	(2,564,000)	(2,152,000)
Balance, end of year	4,003,000	3,851,000	4,003,000	3,851,000
Period-end amount allocated to:
Loans individually evaluated for impairment	0	0	0	0	0
Loans collectively evaluated for impairment	4,003,000	3,851,000	4,003,000	3,851,000	$ 3,923,000
Loans Acquired
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	1,112,000	2,044,000	95,000	418,000
Provision for loan losses	0	0	2,464,000	1,837,000
Charge-offs	(515,000)	(699,000)	(2,862,000)	(910,000)
Recoveries			900,000
Balance, end of year	$ 597,000	$ 1,345,000	$ 597,000	$ 1,345,000