Mortgage Banking Operations - Key Economic Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Measurement Input, Prepayment Rate [Member]
Rates per annum [Abstract]
Servicing asset, measurement input	15.86%	13.36%	13.93%
Measurement Input, Discount Rate [Member]
Rates per annum [Abstract]
Servicing asset, measurement input	10.29%	10.27%	10.28%