Derivative Financial Instruments (Schedule of Offsetting of Derivative Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	$ 1,028	$ 1,799
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Of Assets Presented in the Condensed Consolidated Balance Sheets	1,028	1,799
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(209)	(1,799)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0	0
Net Amount	819	0
HSBC
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	272
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts Of Assets Presented in the Condensed Consolidated Balance Sheets	272
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(59)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0
Net Amount	213
Bank of America
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	62	1,664
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Of Assets Presented in the Condensed Consolidated Balance Sheets	62	1,664
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(10)	(1,664)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0	0
Net Amount	52	0
Wells Fargo
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	694	135
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Of Assets Presented in the Condensed Consolidated Balance Sheets	694	135
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(140)	(135)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0	0
Net Amount	$ 554	$ 0