Loans and Allowance for Loan Losses - Activity in the Allowance for Loan Losses, by Portfolio Segment, for the Current Year (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	$ 56,694	$ 42,086
Provision for loan losses	9,285	9,150
Balance, end of year	60,555	47,614
Loans, Excluding Acquired Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	56,599	41,668
Provision for loan losses	6,821	9,082
Charge-offs	(5,017)	(4,271)
Recoveries	840	728
Net charge-offs	(4,177)	(3,543)
Balance, end of year	59,243	47,207
Period-end amount allocated to:
Loans individually evaluated for impairment	521	444	$ 684
Loans collectively evaluated for impairment	58,722	46,763	55,915
Loans, Excluding Acquired Loans | Other Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	2,419	3,596
Provision for loan losses	1,206	759
Charge-offs	(1,533)	(1,056)
Recoveries	300	94
Net charge-offs	(1,233)	(962)
Balance, end of year	2,392	3,393
Period-end amount allocated to:
Loans individually evaluated for impairment	0	0	0
Loans collectively evaluated for impairment	2,392	3,393	2,419
Loans, Excluding Acquired Loans | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	20,514	7,007
Provision for loan losses	1,874	4,286
Charge-offs	(1,968)	(1,761)
Recoveries	158	69
Net charge-offs	(1,810)	(1,692)
Balance, end of year	20,578	9,601
Period-end amount allocated to:
Loans individually evaluated for impairment	109	18	437
Loans collectively evaluated for impairment	20,469	9,583	20,077
Loans, Excluding Acquired Loans | Real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	29,743	27,281
Provision for loan losses	2,843	3,286
Charge-offs	(374)	(455)
Recoveries	142	302
Net charge-offs	(232)	(153)
Balance, end of year	32,354	30,414
Period-end amount allocated to:
Loans individually evaluated for impairment	412	426	247
Loans collectively evaluated for impairment	31,942	29,988	29,496
Loans, Excluding Acquired Loans | Consumer | Credit cards
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	3,923	3,784
Provision for loan losses	898	751
Charge-offs	(1,142)	(999)
Recoveries	240	263
Net charge-offs	(902)	(736)
Balance, end of year	3,919	3,799
Period-end amount allocated to:
Loans individually evaluated for impairment	0	0	0
Loans collectively evaluated for impairment	3,919	3,799	$ 3,923
Loans Acquired
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period	95	418
Provision for loan losses	2,464	68
Charge-offs	(1,247)	(79)
Balance, end of year	$ 1,312	$ 407