Investment Securities (State And Municipal Obligations, By State And Economic Sector) (Details)	12 Months Ended
	Dec. 31, 2014 Y
Texas
Investment [Line Items]
% of Portfolio	11.00%
Average Life (in years)	4.7
Average Rating (Moody’s)	Aa2
Florida
Investment [Line Items]
% of Portfolio	9.30%
Average Life (in years)	4.1
Average Rating (Moody’s)	Aa3
New York
Investment [Line Items]
% of Portfolio	7.30%
Average Life (in years)	6.5
Average Rating (Moody’s)	Aa2
Ohio
Investment [Line Items]
% of Portfolio	6.00%
Average Life (in years)	5.1
Average Rating (Moody’s)	Aa2
Washington [Member]
Investment [Line Items]
% of Portfolio	5.70%
Average Life (in years)	5.3
Average Rating (Moody’s)	Aa2
General obligation
Investment [Line Items]
% of Portfolio	35.20%
Average Life (in years)	4.9
Average Rating (Moody’s)	Aa2
Lease
Investment [Line Items]
% of Portfolio	15.60%
Average Life (in years)	4.8
Average Rating (Moody’s)	Aa2
Housing
Investment [Line Items]
% of Portfolio	12.90%
Average Life (in years)	3.9
Average Rating (Moody’s)	Aa1
Transportation
Investment [Line Items]
% of Portfolio	12.50%
Average Life (in years)	4.7
Average Rating (Moody’s)	A1
Limited tax
Investment [Line Items]
% of Portfolio	9.10%
Average Life (in years)	6.1
Average Rating (Moody’s)	Aa2