Derivative Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within 12 months		$ 260
Deferred loss balance to loss on early extinguishment of debt	$ 197
Remaining unamortized deferred gain (loss) balance of all previously terminated cash flow hedges		(260)		$ (597)
Remaining deferred gain (loss) balance on all previously terminated fair value hedges		1,700		4,000
Deferred gain balance on terminated fair value hedges expected to be reclassified from long-term debt		1,700
Deferred gain balance to loss on early extinguishment of debt		1,300
Derivative, fair value		1,400		1,400
Gain (loss) on sale of outstanding commitments		(1,600)	$ 2,000
Deferred gains (loss) on discontinuation of cash flow hedge reclassified to earnings		950	1,500
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		108,900		88,800
Unrealized gain on fair value of fixed-rate mortgage loans to customers		1,200	$ 266
Sale of outstanding commitments		135,000		95,000
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts		1,280,000		$ 6,900
Federal Funds Sold [Member]
Derivative [Line Items]
Federal funds sold		75,200
Federal Funds Sold, Counterparty with CCC [Member]
Derivative [Line Items]
Federal funds sold		$ 22,900