Derivatives (Estimated Fair Value of Derivative Assets and Liabilities after Master Netting Agreements and Cash Collateral) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset Excluding Accruals	$ 8,162	$ 8,850
Derivative Liability, Fair Value, Gross Liability Excluding Accruals	0	0
Amounts offset in the consoilidated balance sheets, Assets	0	0
Amounts offset in the consoilidated balance sheets, Liabilities	0	0
Estimated fair value of derivative assets presented in the consolidated balance sheets	8,162	8,850
Estimated fair value of derivative liabilities presented in the consolidated balance sheets	0	0
Net amount of derivative assets after application of master netting agreements and cash collateral	75	178
Net amount of derivative liabilities after application of master netting agreements and cash collateral	0	0
Over the Counter [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset Excluding Accruals	8,162	8,850
Derivative Liability, Fair Value, Gross Liability Excluding Accruals	0	0
Gross estimated fair value of derivative assets	0	0
Gross estimated fair value of derivative liabilities	0	0
Cash collateral on derivative assets	(8,087)	(8,672)
Cash collateral on derivative liabilities	0	0
Securities collateral on derivative assets	0	0
Securities collateral on derivative liabilities	$ 0	$ 0