Derivatives (Effects of Derivatives on Consolidated Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Interest Rate Swap
Derivative [Line Items]
Included in Other Operating Income	$ 90	$ 348

The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations.

No definition available.

Name:	us-gaap_OtherOperatingIncomeExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration