Investment Securities (Schedule of Available-for-Sale Investment Securities Gross Gains and Gross Losses Realized) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Realized gains									$ 9,399	$ 658	$ 405
Realized losses									(1,754)	(335)	(909)
Net realized gains									7,645	323	(504)
Other than temporary impairment charges									0	0	0
Gains (losses) on investment securities, net	$ 1,575	$ 3,305	$ 1,440	$ 1,325	$ (79)	$ (98)	$ (24)	$ 524	7,645	323	(504)
Proceeds from sales and calls of available-for-sale securities									2,208,010	1,515,559	852,330
Proceeds from calls of held-to-maturity securities									$ 734,326	$ 770	$ 0