Derivative Instruments (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Derivative [Line Items]
Remaining unamortized deferred gain (loss) balance of all previously terminated cash flow hedges			$ (130)
Remaining deferred gain balance on all previously terminated fair value hedges			873
Derivative, fair value	$ 5,100		5,800
Gain (loss) on sale of outstanding commitments	(1,700)	$ (1,600)
Collateral requirements	43,300
Deferred gains (loss) on discontinuation of cash flow hedge reclassified to earnings	873	950
Reclassification of hedge-related basis adjustment as a reduction to loss on early extinguishment of debt		1,300
Fixed Rate Residential Mortgage
Derivative [Line Items]
Commitments to fund fixed-rate mortgage loans	87,800		88,200
Unrealized gain on fair value of fixed-rate mortgage loans to customers	(416)	$ 1,200
Sale of outstanding commitments	102,500		126,500
Interest Rate Swap
Derivative [Line Items]
Notional amount of interest rate swap contracts	$ 1,490,000		$ 160,400