SECURITIES (Amortized Cost And Estimated Fair Value Of Available-For-Sale Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
SECURITIES [Abstract]
Maturing in one year or less, Amortized Cost	$ 446,304
Maturing after one year through five years, Amortized Cost	1,334,168
Maturing after five years through ten years, Amortized Cost	53,464
Maturing after ten years, Amortized Cost	246,128
Mortgage-backed securities, Amortized Cost	356,385
Amortized Cost	2,436,449	$ 2,059,445	$ 2,122,249
Maturing in one year or less, Estimated Fair Value	446,972
Maturing after one year through five years, Estimated Fair Value	1,339,338
Maturing after five years through ten years, Estimated Fair Value	54,345
Maturing after ten years, Estimated Fair Value	264,622
Mortgage-backed securities, Estimated Fair Value	362,922
Estimated Fair Value	$ 2,468,199	$ 2,082,329	$ 2,161,125
Maturing in one year or less, Weighted Average Yield	0.92%
Maturing after one year through five years, Weighted Average Yield	1.26%
Maturing after five years through ten years, Weighted Average Yield	5.64%
Maturing after ten years, Weighted Average Yield	5.58%
Mortgage-backed securities, Weighted Average Yield	2.12%