SECURITIES (Amortized Cost And Estimated Fair Value Of Available-For-Sale Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
SECURITIES [Abstract]
Maturing in one year or less, Amortized Cost	$ 588,844
Maturing after one year through five years, Amortized Cost	1,211,049
Maturing after five years through ten years, Amortized Cost	55,472
Maturing after ten years, Amortized Cost	227,422
Mortgage-backed securities, Amortized Cost	329,746
Amortized Cost	2,412,533	$ 2,521,592	$ 2,060,962
Maturing in one year or less, Estimated Fair Value	588,532
Maturing after one year through five years, Estimated Fair Value	1,206,605
Maturing after five years through ten years, Estimated Fair Value	56,682
Maturing after ten years, Estimated Fair Value	239,588
Mortgage-backed securities, Estimated Fair Value	329,888
Estimated Fair Value	$ 2,421,295	$ 2,531,676	$ 2,103,883
Maturing in one year or less, Weighted Average Yield	1.14%
Maturing after one year through five years, Weighted Average Yield	1.37%
Maturing after five years through ten years, Weighted Average Yield	5.78%
Maturing after ten years, Weighted Average Yield	5.49%
Mortgage-backed securities, Weighted Average Yield	2.16%