Securities (Schedule of Information Regarding Securities with Unrealized Losses) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Total temporarily impaired securities Fair Value	$ 275,385	$ 214,027
Total temporarily impaired securities Unrealized Losses	9,023	1,782
Total temporarily impaired securities Fair Value	114,818	128,965
Total temporarily impaired securities Unrealized Losses	4,635	1,972
Total temporarily impaired securities Fair Value	390,203	342,992
Total temporarily impaired securities Unrealized Losses	13,658	3,754
Government-sponsored enterprise securities [Member]
AFS Fair Value	15,615	10,897
AFS Unrealized Losses	385	103
AFS Fair Value	2,922	2,970
AFS Unrealized Losses	78	30
Total temporarily impaired securities Fair Value	18,537	13,867
Total temporarily impaired securities Unrealized Losses	463	133
Mortgage-backed securities [Member]
AFS Fair Value	224,713	192,702
AFS Unrealized Losses	8,050	1,582
AFS Fair Value	110,958	125,060
AFS Unrealized Losses	4,495	1,877
Total temporarily impaired securities Fair Value	335,671	317,762
Total temporarily impaired securities Unrealized Losses	12,545	3,459
Corporate bonds [Member]
AFS Fair Value	25,697	2,500
AFS Unrealized Losses	530	49
AFS Fair Value	938	935
AFS Unrealized Losses	62	65
Total temporarily impaired securities Fair Value	26,635	3,435
Total temporarily impaired securities Unrealized Losses	592	114
State and local governments [Member]
HTM Fair Value	9,360	7,928
HTM Unrealized Losses	58	48
AFS Fair Value
AFS Unrealized Losses
Total temporarily impaired securities Fair Value	9,360	7,928
Total temporarily impaired securities Unrealized Losses	$ 58	$ 48