Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) $ in Thousands	Jun. 30, 2017 USD ($)
Available-for-sale Securities [Abstract]
Due within one year, Amortized Cost	$ 99,775
Due after one year through five years, Amortized Cost	461,043
Due after five years through ten years, Amortized Cost	726,133
Due after ten years, Amortized Cost	980,724
No stated maturity date, Amortized Cost Basis	5,284
Total investment securities available-for-sale, Amortized Cost	2,272,959
Due within one year, Fair Value	99,740
Due after one year through five years, Fair Value	464,716
Due after five years through ten years, Fair Value	724,520
Due after ten years, Fair Value	970,563
No stated maturity date, Fair Value	5,097
Total investment securities available-for-sale, Fair Value	$ 2,264,636