Investment Securities (State And Municipal Obligations, By State And Economic Sector) (Details)	Sep. 30, 2012 Y
Sector Classification, Texas [Member]
Investment [Line Items]
% of Portfolio	9.90%
Average Life (in years)	5.2
Average Rating (Moody's)	Aa1
Sector Classification, Florida [Member]
Investment [Line Items]
% of Portfolio	9.50%
Average Life (in years)	4.7
Average Rating (Moody's)	Aa2
Sector Classification, Washington [Member]
Investment [Line Items]
% of Portfolio	6.40%
Average Life (in years)	4.2
Average Rating (Moody's)	Aa2
Sector Classification, Ohio [Member]
Investment [Line Items]
% of Portfolio	5.50%
Average Life (in years)	5.3
Average Rating (Moody's)	Aa2
Sector Classification Arizona [Member]
Investment [Line Items]
% of Portfolio	4.70%
Average Life (in years)	3.4
Average Rating (Moody's)	Aa3
Sector Classification, General Obligation [Member]
Investment [Line Items]
% of Portfolio	31.80%
Average Life (in years)	4.8
Average Rating (Moody's)	Aa2
Sector Classification, Housing [Member]
Investment [Line Items]
% of Portfolio	20.00%
Average Life (in years)	6.9
Average Rating (Moody's)	Aa1
Sector Classification, Transportation [Member]
Investment [Line Items]
% of Portfolio	12.80%
Average Life (in years)	3.7
Average Rating (Moody's)	Aa3
Sector Classification, Lease [Member]
Investment [Line Items]
% of Portfolio	11.80%
Average Life (in years)	3.4
Average Rating (Moody's)	Aa3
Sector Classification, Limited Tax [Member]
Investment [Line Items]
% of Portfolio	7.50%
Average Life (in years)	5.6
Average Rating (Moody's)	Aa1