Investment Securities (State And Municipal Obligations, By State And Economic Sector) (Details)	Jun. 30, 2012 Y
Sector Classification, Texas [Member]
Investment [Line Items]
% of Portfolio	10.30%
Average Life (in years)	5.3
Average Rating (Moody's)	Aa1
Sector Classification, Florida [Member]
Investment [Line Items]
% of Portfolio	8.80%
Average Life (in years)	4.5
Average Rating (Moody's)	Aa2
Sector Classification, Washington [Member]
Investment [Line Items]
% of Portfolio	6.00%
Average Life (in years)	3.8
Average Rating (Moody's)	Aa2
Sector Classification Arizona [Member]
Investment [Line Items]
% of Portfolio	5.10%
Average Life (in years)	3.7
Average Rating (Moody's)	Aa3
Sector Classification, Ohio [Member]
Investment [Line Items]
% of Portfolio	4.80%
Average Life (in years)	4.9
Average Rating (Moody's)	Aa2
Sector Classification, General Obligation [Member]
Investment [Line Items]
% of Portfolio	27.60%
Average Life (in years)	4.3
Average Rating (Moody's)	Aa2
Sector Classification, Housing [Member]
Investment [Line Items]
% of Portfolio	21.70%
Average Life (in years)	5.5
Average Rating (Moody's)	Aa1
Sector Classification, Transportation [Member]
Investment [Line Items]
% of Portfolio	13.90%
Average Life (in years)	3.9
Average Rating (Moody's)	Aa3
Sector Classification, Lease [Member]
Investment [Line Items]
% of Portfolio	13.50%
Average Life (in years)	3.5
Average Rating (Moody's)	Aa3
Sector Classification, Limited Tax [Member]
Investment [Line Items]
% of Portfolio	6.10%
Average Life (in years)	5.1
Average Rating (Moody's)	Aa1