Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Available-for-sale Securities [Abstract]
Due within one year, Amortized Cost	$ 38,596
Due after one year through five years, Amortized Cost	515,056
Due after five years through ten years, Amortized Cost	679,739
Due after ten years, Amortized Cost	1,060,362
Total investment securities available-for-sale, Amortized Cost	2,299,037
Due within one year, Fair Value	38,717
Due after one year through five years, Fair Value	517,283
Due after five years through ten years, Fair Value	672,018
Due after ten years, Fair Value	1,045,476
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis	5,284
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	5,083
Total investment securities available-for-sale, Fair Value	$ 2,278,577