Investment Securities (Carrying Value And Fair Value Of Securities Held-To-Maturity) (Details) (USD $) In Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2011		Dec. 31, 2010
Carrying value	$ 178.1	[1]	$ 195.9	[1]
Fair value	180.8		197.6
U.S. Treasury Agency Obligations [Member]
Carrying value	105.2		119.8
Gross unrecognized gains	0.8		0.7
Fair value	106.0		120.5
U.S. Government And Government Sponsored Agency Guaranteed [Member]
Carrying value	53.6		56.9
Gross unrecognized gains	1.9		1.0
Fair value	55.5		57.9
State and Municipal [Member]
Carrying value	0.4		0.4
Gross unrecognized gains	0		0
Fair value	0.4		0.4
Foreign Government [Member]
Carrying value	18.9		18.8
Gross unrecognized gains	0		0
Fair value	18.9		18.8
Total Debt Securities Held-to-Maturity [Member]
Carrying value	178.1		195.9
Gross unrecognized gains	2.7		1.7
Fair value	$ 180.8		$ 197.6

[1] Recorded at amortized cost less impairment on securities that have credit-related impairment.