Fair Value - Schedule of Significant Unobservable Inputs Used in Fair Value Measurement of Real Estate Owned (Details) - Non-recurring Measurement Basis [Member] - Real Estate Owned [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Loss severity	0.00%	0.00%
Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Loss severity	78.76%	61.61%
Weighted Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Loss severity	6.16%	7.30%