Mergers and acquisitions - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - Clayton Banks $ in Thousands	Jul. 31, 2017 USD ($)
Assets
Cash and cash equivalents	$ 49,059
Investment securities	59,493
FHLB stock	3,409
Loans	1,060,508
Premises and equipment	19,480
Other real estate owned	6,888
Core deposit intangible	9,060
Other assets	6,138
Total assets	1,214,035
Liabilities
Interest-bearing deposits	670,054
Non-interest bearing deposits	309,464
Borrowings	84,831
Accrued expenses and other liabilities	5,245
Total liabilities	1,069,594
Net assets acquired	144,441
Historical Cost Basis
Assets
Cash and cash equivalents	49,059	[1]
Investment securities	59,108	[1]
FHLB stock	3,409	[1]
Loans	1,075,441	[1]
Allowance for loan losses	(19,985)	[1]
Premises and equipment	15,011	[1]
Other real estate owned	6,244	[1]
Other assets	15,322	[1]
Total assets	1,203,609	[1]
Liabilities
Interest-bearing deposits	669,745	[1]
Non-interest bearing deposits	309,464	[1]
Borrowings	84,110	[1]
Accrued expenses and other liabilities	4,577	[1]
Total liabilities	1,067,896	[1]
Net assets acquired	135,713	[1]
Fair Value Adjustments
Assets
Investment securities	385
Loans	(14,933)
Allowance for loan losses	19,985
Premises and equipment	4,469
Other real estate owned	644
Core deposit intangible	9,060
Other assets	(9,184)
Total assets	10,426
Liabilities
Interest-bearing deposits	309
Borrowings	721
Accrued expenses and other liabilities	668
Total liabilities	1,698
Net assets acquired	$ 8,728

[1] Amounts include certain reclassifications of opening balances to conform to the Company’s presentation.