Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Operating Loss Carryforwards [Line Items]
Provisional income tax expense (benefit)	$ 14,486,000
Heritage Financial Group
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	$ 0	$ 0	$ 0