Investment in Securities (Schedule of the Fair Values of Securities with Unrealized Losses) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investment [Line Items]
Estimated fair value, less than 12 months	$ 22,095	$ 3,638
Estimated fair value, 12 months or more		1,208
Estimated fair value, total	22,095	4,846
Unrealized losses, less than 12 months	175	5
Unrealized losses, 12 months or more		8
Unrealized losses, total	175	13
State and Political Subdivisions [Member]
Investment [Line Items]
Estimated fair value, less than 12 months	19,000	3,638
Estimated fair value, 12 months or more		1,208
Estimated fair value, total	19,000	4,846
Unrealized losses, less than 12 months	174	5
Unrealized losses, 12 months or more		8
Unrealized losses, total	174	13
U.S. government agencies [Member]
Investment [Line Items]
Estimated fair value, less than 12 months	3,095
Estimated fair value, 12 months or more
Estimated fair value, total	3,095
Unrealized losses, less than 12 months	1
Unrealized losses, 12 months or more
Unrealized losses, total	1
Certificates of Deposit [Member]
Investment [Line Items]
Estimated fair value, less than 12 months
Estimated fair value, 12 months or more
Estimated fair value, total
Unrealized losses, less than 12 months
Unrealized losses, 12 months or more
Unrealized losses, total