Derivative Financial Instruments (Schedule of Offsetting of Derivative Liabilities) (Details) - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2017
Offsetting of Derivative Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$ 507	$ 8,192
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Of Liabilities Presented in the Condensed Consolidated Balance Sheets	507	8,192
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(507)	(1,799)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0	0
Net Amount	0	6,393
Bank of America
Offsetting of Derivative Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	318	7,815
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Of Liabilities Presented in the Condensed Consolidated Balance Sheets	318	7,815
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(318)	(1,664)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0	0
Net Amount	0	6,151
Wells Fargo
Offsetting of Derivative Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	189	377
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Of Liabilities Presented in the Condensed Consolidated Balance Sheets	189	377
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Financial Instruments	(189)	(135)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets: Cash Collateral Pledged	0	0
Net Amount	$ 0	$ 242