Derivative Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Derivative [Line Items]
Remaining unamortized deferred gain (loss) balance of all previously terminated cash flow hedges	$ (65)		$ (130)
Cash flow hedge gain (loss) to be reclassified within 12 months	65
Remaining deferred gain balance on all previously terminated fair value hedges	436		873
Deferred gain balance on terminated fair value hedges expected to be reclassified from long-term debt	436
Derivative, fair value	5,400		5,800
Gain (loss) on sale of outstanding commitments	(2,500)	$ (933)
Collateral requirements	49,100
Deferred gains (loss) on discontinuation of cash flow hedge reclassified to earnings	437	515
Reclassification of hedge-related basis adjustment as a reduction to loss on early extinguishment of debt		1,300
Fixed Rate Residential Mortgage [Member]
Derivative [Line Items]
Commitments to fund fixed-rate mortgage loans	100,500		88,200
Unrealized gain on fair value of fixed-rate mortgage loans to customers	674	$ 782
Sale of outstanding commitments	112,000		126,500
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts	$ 1,410,000		$ 85,700