Derivative Financial Instruments Schedule of Offsetting of Derivate Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$ 8,192	$ 1,705
Gorss Amount Offset in the Consolidated Balance Sheets	0	0
Net Amounts of LIabilities Presented in the Consolidated Balance Sheets	8,192	1,705
Financial Instruments	(1,799)	(1,705)
Cash Collateral Pledged	0	0
Net Amounts	6,393	0
Bank of America [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	7,815
Gorss Amount Offset in the Consolidated Balance Sheets	0
Net Amounts of LIabilities Presented in the Consolidated Balance Sheets	7,815
Financial Instruments	(1,664)
Cash Collateral Pledged	0
Net Amounts	6,151
J.P. Morgan Chase [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities		442
Gorss Amount Offset in the Consolidated Balance Sheets		0
Net Amounts of LIabilities Presented in the Consolidated Balance Sheets		442
Financial Instruments		(442)
Cash Collateral Pledged		0
Net Amounts		0
Wells Fargo Bank [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	377	1,263
Gorss Amount Offset in the Consolidated Balance Sheets	0	0
Net Amounts of LIabilities Presented in the Consolidated Balance Sheets	377	1,263
Financial Instruments	(135)	(1,263)
Cash Collateral Pledged	0	0
Net Amounts	$ 242	$ 0