Basis of Presentation Accounting Changes (Details)	3 Months Ended
	Mar. 31, 2018 USD ($)
Accounting Standards Update 2016-01 [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 33,000
Accounting Standards Update 2018-02 [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 492,000