Financial Derivatives - Hedging Description (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ (22,600)	$ (19,700)	$ (18,000)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	1,200	200	11
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	1,400
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net of Tax	$ 900
Maximum Length of Time Hedged in Interest Rate Cash Flow Hedge	10 years
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	$ 0	$ 0	$ 0