Financial Information (Schedule of Accounting Changes) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
New Accounting Pronouncement or Change in
Other Assets	$ 1,435,379	$ 1,436,291	$ 1,417,071
Term borrowings	$ 1,065,651	1,312,677	1,339,940
Accounting Standards Update 201503 [Member]
New Accounting Pronouncement or Change in
Other Assets		(2,499)	(1,246)	$ (2,764)
Term borrowings		$ (2,499)	$ (1,246)	$ (2,764)