Fair Value of Financial Instruments - Level 3 Quantitative Information (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Impaired loans
Fair Value Inputs, Quantitative Information [Abstract]
Selling cost	8.00%	8.00%
Other real estate owned, net
Fair Value Inputs, Quantitative Information [Abstract]
Selling cost	8.00%	8.00%
Minimum | Impaired loans
Fair Value Inputs, Quantitative Information [Abstract]
Market rate for borrower (discount rate)	3.25%	3.25%
Maximum | Impaired loans
Fair Value Inputs, Quantitative Information [Abstract]
Market rate for borrower (discount rate)	9.80%	9.80%