Derivative Financial Instruments (Rollforward of Amounts in Accumulated Other Comprehensive Income Related to Interest Rate Swaps Designated as Cash Flow Hedges) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Amount of gain recognized in other comprehensive income	$ (1,160)	$ 4,958	$ 10,473
Interest rate derivatives
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Unrealized gain at beginning of period	11,902	6,944
Amount reclassified from accumulated other comprehensive income to interest expense on deposits and junior subordinated debentures	(7,313)	(19)
Amount of gain recognized in other comprehensive income	6,153	4,977
Unrealized gain at end of period	$ 10,742	$ 11,902	$ 6,944