Accumulated Other Comprehensive Income (Changes in Other Comprehensive Income by Components) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net unrealized gains on securities available for sale
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	$ 2,209,000	$ 16,924,000	$ 25,765
Other Comprehensive Income Loss Before Reclassifications Net Of Tax	(11,563,000)	(26,661,000)	(5,822,000)
Other-than-temporary impairment losses on investment securities			(4,662,000)
Reclassification Out Of Accumulated Other Comprehensive Income	6,716,000	11,946,000	1,643,000
Other Comprehensive Income (Loss) Other Net Of Tax	(4,847,000)	(14,715,000)	(8,841,000)
Ending balance	(2,638,000)	2,209,000	16,924,000
Net unrealized loss on cash flow hedges
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	(613,000)	(2,927,000)	(6,054)
Other Comprehensive Income Loss Before Reclassifications Net Of Tax	(186,000)	(1,628,000)	(3,019,000)
Other-than-temporary impairment losses on investment securities			0
Reclassification Out Of Accumulated Other Comprehensive Income	488,000	3,942,000	6,146,000
Other Comprehensive Income (Loss) Other Net Of Tax	302,000	2,314,000	3,127,000
Ending balance	(311,000)	(613,000)	(2,927,000)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	1,596,000	13,997,000	19,711
Other Comprehensive Income Loss Before Reclassifications Net Of Tax	(11,749,000)	(28,289,000)	(8,841,000)
Other-than-temporary impairment losses on investment securities			(4,662,000)
Reclassification Out Of Accumulated Other Comprehensive Income	7,204,000	15,888,000	7,789,000
Other Comprehensive Income (Loss) Other Net Of Tax	(4,545,000)	(12,401,000)	(5,714,000)
Ending balance	$ (2,949,000)	$ 1,596,000	$ 13,997,000