Derivative Financial Instruments Scheduel of Offsetting of Derivative Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	$ 1,799	$ 8,763
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1,799	8,763
Financial Instruments	(1,799)	(1,705)
Cash Collateral Pledged	0	0
Net Amount	0	7,058
Bank of America [Member]
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	1,664
Gross Amounts Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1,664
Financial Instruments	(1,664)
Cash Collateral Pledged	0
Net Amount	0
J.P. Morgan Chase [Member]
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets		1,492
Gross Amounts Offset in the Consolidated Balance Sheets		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets		1,492
Financial Instruments		(442)
Cash Collateral Pledged		0
Net Amount		1,050
Wells Fargo Bank [Member]
Offsetting of Derivative Assets [Line Items]
Gross Amounts of Recognized Assets	135	7,271
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	135	7,271
Financial Instruments	(135)	(1,263)
Cash Collateral Pledged	0	0
Net Amount	$ 0	$ 6,008