Financial Derivatives - Hedging Description (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ (1,900)	$ (4,000)	$ (6,900)	$ (12,900)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	400	500	1,400	1,500
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	1,200		1,200
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net of Tax	800		800
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	$ 0	$ 0	$ 0	$ 0