Derivatives and Hedging Activities - Tabular Disclosure Offsetting Derivatives (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts of Recognized Assets	$ 627	$ 199
Gross Amounts of Recognized Liabilities	0	(3,547)
Gross Amounts Offset in the Consolidated Balance Sheets	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	627	199
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	0	(3,547)
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Amount	$ 627	$ (3,348)