Fair Value Measurements (Level 3 Fair Value Measurements- Qualitative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value estimate	$ 4,504	$ 5,168	$ 273
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value estimate	$ 4,279	$ 4,500
Fair Value, Measurements, Recurring [Member] | Minimum [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	3.00%	3.00%
Fair Value, Measurements, Recurring [Member] | Maximum [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	6.00%	6.00%
Fair Value, Measurements, Recurring [Member] | Average [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	5.00%	5.00%
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value estimate	$ 420	$ 993
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Assets [Member] | Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	75.00%	75.00%
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Assets [Member] | Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	90.00%	90.00%
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Assets [Member] | Average [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	89.00%	89.00%
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value estimate	$ 195	$ 325
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	75.00%	75.00%
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	90.00%	90.00%
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | Average [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	89.00%	89.00%
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Real Estate Secured [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value estimate	$ 2,736	$ 1,371
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Real Estate Secured [Member] | Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	0.00%	0.00%
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Real Estate Secured [Member] | Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	15.00%	15.00%
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Real Estate Secured [Member] | Average [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	10.00%	10.00%
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Non Real Estate Secured [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value estimate	$ 1,890	$ 5,551
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Non Real Estate Secured [Member] | Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	0.00%	0.00%
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Non Real Estate Secured [Member] | Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	10.00%	10.00%
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans Non Real Estate Secured [Member] | Average [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Range (weighted average)	5.00%	5.00%